The Dupondius denomination
The dupondius (Latin two-pounder) was a brass coin used during the Roman Empire and Roman Republic valued at 2 aes (1/2 of a sestertius or 1/8 of a denarius).

The dupondius was introduced during the Roman Republic as a large bronze cast coin, although even at introduction it weighed less than 2 pounds. The initial coins featured the bust of Roma on the obverse and a six-spoked wheel on the reverse.

With the coinage reform of Augustus in about 23 BC, the sestertius and dupondius were produced in a golden colored copper-alloy called orichalcum (brass).

The dupondius was normally further distinguished from the similarly sized as with the addition of a radiate crown to the bust of the emperor in 66 AD during the reign of Nero.
Dupondius
/Files/Images/Coinsite/CoinDB/Antonia(0).jpg
An AE Dupondius struck 42 AD in Rome
Obverse: ANTONIA AVGVSTA, draped bust right

Reverse: TI CLAVDIVS CAESAR AVG P M TR P IMP S-C, Claudius, togate, standing left, holding simpulum

Diameter: 26 mm
Die Orientation: 0 H
Weight: 12.6 g

Reverse very worn, but a nice portrait for the grade

Cohen 6, RCV 1903
/Files/Images/Coinsite/CoinDB/IMG_0372x.jpg
An AE Dupondius struck 157-158 AD in Rome
Obverse: radiate head right; ANTONINVS AVG__PIVS P P TR P XXI

Reverse: distyle shrine with arched roof containing statue of the Genius of the Senate, togate, raising hand, holding eagle-tipped scepter, standing on pedestal; COS__IIII / S C

Diameter: 24 mm
Die Orientation: -
Weight: 13.04 g
No notes for this coin
RIC 989
/Files/Images/Coinsite/CoinDB/A044.jpg
An AE Dupondius struck 158-159 AD in Rome
Obverse: ANTONINVS AVG PIVS P P TR P XXII, Bust of Antoninus Pius facing right, wearing crown, and slight drapery

Reverse: VOTA SOL DECENN II, Antoninus Pius, standing facing left, sacrificing with patera over tripod, left arm at side; by altar, bull reclining; S-C in fields; COS IIII in exergue

Diameter: 26 mm
Die Orientation: 12 H
Weight: 13.71 g
RIC III Antoninus Pius 1019 is Head of Antoninus Pius facing right, wearing crown, this is a bust with a slight drapery
RIC III Antoninus Pius 1019 var. (bust, slight drapery)
/Files/Images/Coinsite/CoinDB/A029-1.jpg
An AE Dupondius struck 147-148 AD in Rome
Obverse: ANTONINVS AVG PIVS P P TR P XI, Head of Antoninus Pius facing right, wearing crown (mark of value)

Reverse: COS IIII, Antoninus Pius standing facing left, wearing toga, sacrificing with patera over tripod; SC in fields; VOTA in exergue

Diameter: 27 mm
Die Orientation: 5 H
Weight: 10.85 g
No notes for this coin
RIC III Antoninus Pius 849
/Files/Images/Coinsite/CoinDB/A060.jpg
An AE Dupondius struck 155-156 AD in Rome
Obverse: ANTONINVS AVG PIVS P P IMP II, Head of Antoninus Pius, radiate, right

Reverse: TR POT XIX COS IIII, Annona, draped, seated right, holding cornucopiae in both hands: modius with grain stalks at her feet; SC in exergue

Diameter: 25 mm
Die Orientation: 10 H
Weight: 10.87 g
RIC III 956 is an As, coin is unknown as a Dupondius in RIC, however 4 examples have sold on acsearch, 2 of them have a slight drapery on right shoulder, mine is pretty worn but I believe there is no drapery
RIC III Antoninus Pius 956 var. (denomination)
/Files/Images/Coinsite/CoinDB/A062.jpg
An AE Dupondius struck 155-156 AD in Rome
Obverse: ANTONINVS AVG PIVS P P IMP II, Head of Antoninus Pius, radiate, right

Reverse: TR POT XIX COS IIII, Providentia, standing left, pointing with right hand at large globe and holding scepter; SC in fields

Diameter: 27 mm
Die Orientation: 6 H
Weight: 13.45 g
No notes for this coin
RIC III Antoninus Pius 953
/Files/Images/Coinsite/CoinDB/Untitled(14).png
An AE Dupondius struck 15-14 BC in Rome
Obverse: AVGVSTVS TRIBVNIC POTEST, Inscription in three lines within oak wreath

Reverse: CN PISO CN F IIIVIR AAAFF, Inscription around large SC

Diameter: 27 mm
Die Orientation: 4 H
Weight: 11.07 g
Gnaeus Calpurnius Piso, son of Gnaeus Calpurnius Piso (Consul in 23 BC) as Moneyer

RIC dates to 15 BC and 14 BC comes from:
The_moneyer_issues_under_Augustus.pdf by C.G.J. Pannekeet

The obverse inscription translates to "Augustus, Holding power of the Tribune of the Plebs"

The reverse inscription translates to "Gnaeus Piso, son of Gnaeus, One of three magistrates responsible for the casting and striking of gold, silver, and bronze coinage.
SC stands for "senatus consultum", a decree of the senate.
RIC I (2nd Ed.) 381
/Files/Images/Coinsite/CoinDB/aug6_bestever_really.jpg
An AE Dupondius struck 18 B.C. in Rome
Obverse: AVGVSTVS TRIBVNIC POTEST Legend in oak wreath

Reverse: C . ASINIVS IIIVIR A A A F F around S C

Diameter: 28 mm
Die Orientation: 1 H
Weight: 11.66 g
Ex. William C Boyd Collection , Baldwins Auction (42) 9/26/2005
c.f. RIC 372
(9) Clodius Albinus
/Files/Images/Coinsite/CoinDB/01_IMG_4296(0).jpg
An AE As | Dupondius struck 194-195 AD in Rome
Obverse: bare head right; D CL SEPT AL_BIN CAES

Reverse: Saeculum Frugiferum standing left, holding caduceus with grain ears and trident; SAECVLO FRVGIFERO COS II / S__C

Diameter: 23 mm
Die Orientation: -
Weight: 10.72 g
No notes for this coin
RIC IVa, 61 (C. 72); BMC V, 549 (Pl. 23, 8); C. 72 (Paris)
(10) Crispina
/Files/Images/Coinsite/CoinDB/424_Crispina.JPG
An AE As | Dupondius struck 180-182 AD in Rome
Obverse: draped bust right; CRISPINA__AVGVSTA

Reverse: Juno standing left holding scepter and patera; IVNO LV_CINA / S__C

Diameter: -
Die Orientation: -
Weight: 12.92 g
No notes for this coin
RIC III 680, Cohen 24, BMCRE IV 433, SRCV II 6018
/Files/Images/Coinsite/CoinDB/Faustina_II_-_Pudicitiax.jpg
An AE Dupondius struck 147-150 AD in Rome
Obverse: draped bust right; FAVSTINAE AVG__PII AVG FIL

Reverse: Pudicitia seated left, pulling veil and holding scepter; PVDIC_ITIA / S C

Diameter: 25 mm
Die Orientation: -
Weight: 13.54 g
ex VAuctions Grand Reopening 2008
RIC 1404b, Cohen 187, BMC 2159
/Files/Images/Coinsite/CoinDB/Untitled(163).jpg
An AE Dupondius struck 37-41 AD in Rome
Obverse: GERMANICVS CAESAR, Germanicus, bare-headed and cloaked, standing in quadriga, right, holding eagle tipped scepter

Reverse: SIGNIS RECEPT DEVICTIS GERM S C, Germanicus bare-headed and cuirassed, right, with tunic standing, left, right hand raised and left holding aquila

Diameter: 29 mm
Die Orientation: 6 H
Weight: 14.19 g
No notes for this coin
RIC I (2nd Ed.) Gaius 57
/Files/Images/Coinsite/CoinDB/Roma_Auction_Pic_(Obv_and_Rev)(26).jpg
An AE Dupondius struck AD 37-41 in Rome
Obverse: GERMANICVS CAESAR, Germanicus, bare-headed, draped and holding eagle-tipped sceptre and reins, driving triumphal quadriga right; chariot decorated with figure of Victory advancing right

Reverse: SIGNIS RECEPT DEVICTIS GERM, Germanicus, bare-headed, wearing cuirass and short tunic, standing left, cloak over arm in which he cradles aquila, and extending hand in gesture of command; S-C across lower fields

Diameter: 28 mm
Die Orientation: 6 H
Weight: 11.46 g
No notes for this coin
RIC 57 (Gaius); BMCRE 93-100 (Caligula); BN 140-51 (Caligula)
(14) Hadrian
/Files/Images/Coinsite/CoinDB/Hadrian_Salus_dupondius.jpg
An AE Dupondius struck 119-121 AD in Rome
Obverse: radiate bust right, draped shoulder, bare chest; IMP CAESAR TRAIANVS HADRIANVS AVG P M TR P COS III

Reverse: Salus-Fortuna standing left, stepping on globe, holding patera and rudder; SALVS P_VBLICA / S__C

Diameter: 26 mm
Die Orientation: -
Weight: 14.78 g
No notes for this coin
RIC II 604a, BMCRE III 1237, Cohen 1358, SRCV II 3668
(15) Hadrian
/Files/Images/Coinsite/CoinDB/Roma_Auction_Pic_(Obv_and_Rev)(21).JPG
An AE Dupondius struck AD 126 in Rome
Obverse: HADRIANVS AVGVSTVS, radiate head right, light drapery on far shoulder

Reverse: COS III, Aequitas seated left, holding scales and cornucopiae; S C in exergue

Diameter: 26 mm
Die Orientation: 5 H
Weight: 10.41 g
No notes for this coin
RIC 655; Sear 3657
/Files/Images/Coinsite/CoinDB/AurelisDupondius.jpg
An AE Dupondius struck 176-177 AD in Rome
Obverse: [M ANTONI]NVS AVG GERM SARM TR P XXXI, Radiate bust right

Reverse: [IMP VIII COS III P P] PAX AETERNA AVG, Pax standing l., holding cornucopiae and setting fire to a pile of arms, S - C in fields

Diameter: 25 mm
Die Orientation: 0 H
Weight: 10.5 g
Rated C for common in RIC, but the second example online (as far as I can find). Struck between December 176 and the fall of 177 AD
RIC3 1203
(17) Nero
/Files/Images/Coinsite/CoinDB/NEROAS.jpg
An AE Dupondius struck 54-68 AD in Lugdunum
Obverse: NERO CLAVD CAESAR AVG GER P M TR P IMP P P, laureate head left

Reverse: SECVRITAS AVGVSTI S-C, II in ex, Securitas seated right, holding veil above her head, altar at feet right.

Diameter: 30 mm
Die Orientation: -
Weight: 12.2 g
100
RIC 407
(18) Nerva
/Files/Images/Coinsite/CoinDB/Roma_Auction_Pic_(Obv_and_Rev)(42).jpg
An AE Dupondius struck AD 97 in Rome
Obverse: [IMP] NERVA CAES AVG P M TR P [COS III] P P, radiate head right

Reverse: FORTVNA AVGVST, Fortuna standing left, holding rudder and cornucopiae; S-C across fields

Diameter: 23 mm
Die Orientation: 6 H
Weight: 12.96 g
No notes for this coin
RIC 84; BMCRE 123
(19) Tiberius
/Files/Images/Coinsite/CoinDB/Untitled(97).jpg
An AE Dupondius struck 19-21 AD in Commagene
Obverse: TI CAESAR DIVI AVGVSTI F AVGVSTVS, Head of Tiberius facing right, wearing laurel wreath

Reverse: PONT MAXIM COS III IMP VII TR POT XXI, Upright caduceus between two crossed cornucopias framing two crossed branches

Diameter: 29 mm
Die Orientation: 12 H
Weight: 14.76 g
In 17 AD when Antiochus III of Commagene died, Tiberius annexed Commagene to the province of Syria. RIC is confident in the attribution to this mint, RPC is hesitant with Antioch being another possibility based on find evidence. RIC dates to 19-21 AD, whereas RPC goes with 19-20 AD.
RIC I (Second Edition) Tiberius 89, RPC I 3868
(20) Tiberius
/Files/Images/Coinsite/CoinDB/Untitled(102).jpg
An AE Dupondius struck 19-21 AD in Commagene
Obverse: TI·CAESAR·DIVI·AVGVSTI·F·AVGVSTVS, Head of Tiberius facing right, wearing laurel wreath

Reverse: Blundered Inscription, Caduceus between crossed cornucopias

Diameter: 30 mm
Die Orientation: 12 H
Weight: 9.6 g
Because of the blundered and weakly struck at the point of interest inscription, I'm uncertain whether the inscription ends TR POT XXI or II

In 17 AD when Antiochus III of Commagene died, Tiberius annexed Commagene to the province of Syria. RIC is confident in the attribution to this mint, RPC is hesitant with Antioch being another possibility based on find evidence. RIC dates to 19-21 AD, whereas RPC goes with 19-20 AD.
RIC I (2nd Ed.) Tiberius 89-90; RPC I 3868-9
(21) Trajan
/Files/Images/Coinsite/CoinDB/RI-NA-008.jpg
An AE Dupondius struck 116-117 in Rome
Obverse: IMP CAES NER TRAIANO OPTIMO AVG GER DAC PARTHICO P M TR P COS VI P P, Radiate draped bust right

Reverse: SENATVS POPVLVSQVE ROMANVS, Trajan advancing right with head turned left, between two trophies; SC below

Diameter: 23 mm
Die Orientation: 12 H
Weight: -
Found on a building site in Colchester in the 1970s. Trophies represent victories in the Parthian campaign of 115-116 AD, and likely represent Trajan's 12th and 13th Imperatorial acclamations, according to Strack p226, via someone on vcoins.
RIC 676
/Files/Images/Coinsite/CoinDB/VESPASIAN(1).jpg
An AE Dupondius struck 77-78 A.D. in Rome
Obverse: IMP CAES VESPASIAN AVG COS VIII P P, laureate bust right

Reverse: FORTVNAE REDVCI, Fortuna standing left holding rudder and cornucopiae, S-C across fields

Diameter: 26 mm
Die Orientation: -
Weight: 10 g
35
RIC 1215
/Files/Images/Coinsite/CoinDB/Vespasian_dupondius_Felicitas.jpg
An AE Dupondius struck 76 AD in Rome
Obverse: Radiate head right; IMP CAES VESP AVG P M T P COS VII / S__C

Reverse: Felicitas holding caduceus and cornucopiae; FELICITAS__PVBLICA

Diameter: 27 mm
Die Orientation: 0 H
Weight: 13.76 g
No notes for this coin
RIC II 887; Cohen 488
/Files/Images/Coinsite/CoinDB/Vespasian_dupondius_ROMA.jpg
An AE Dupondius struck 71 AD in Rome
Obverse: Radiate head right; IMP CAES VESPASIAN AVG COS III

Reverse: Roma left seated on cuirass, holding wreath and parazonium shield and helmet to the right; ROMA / S C

Diameter: 0 mm
Die Orientation: 0 H
Weight: 13 g
No notes for this coin
RIC II, part 1, 277
/Files/Images/Coinsite/CoinDB/Vespasian_(Obv_and_Rev)_7.jpg
An AE Dupondius struck AD 74 in Rome
Obverse: IMP CAESAR VESPASIAN AVG, laureate head right

Reverse: PON MAX TR POT P P COS V CENS, winged caduceus between crossed cornucopiae

Diameter: 28 mm
Die Orientation: 6 H
Weight: 14.2 g
Struck in Rome for use in Syria
RIC² 756; RPC 1982