Mint Error Coin Chronicles: Double Struck Coins

Numismatic Guaranty Company® (NGC®) is the world’s leading authority on mint errors, a popular segment of numismatics. In Mint Error Coin Chronicles, we take an in-depth look at a specific kind of mint error. This month’s topic is Double Struck coins.

Double Struck coins are as old as coinage itself, since they involve a dynamic part of the process that is prone to mistakes. Hand-struck coins of the ancient world typically required more than one strike (sometimes several!) to raise the relief, and sometimes they were so poorly centered that they needed to be struck again.

Look closely at this silver tetradrachm struck just after the lifetime of Alexander III "the Great" (336-323 B.C.). At the right side of the obverse, you can see an extra chin and lips to the right of Heracles' head. Those were from the first strike (or strikes), after which the coin rotated between the dies and was subsequently struck at a different rotation. The second strike is also evident on the reverse, where the eagle near Zeus' head is a leftover from the first strike. This coin is offered in a Heritage Auctions sale in August 2024.

Click images to enlarge.

The Double Strike error continued even as mechanical innovations sped up the process of minting coins. This 1794 Head of 94 Cent is an example of an early error produced by the US Mint. The coins is Double Struck, and both strikes are off-center. With a grade of NGC Mint Error MS 66 BN, it is also one of the finest examples of this coin in existence, and its unusual appearance is likely why it is so well-preserved: because it was set aside. This coin is one of the top highlights of a Heritage Auctions sale in August 2024; you can read more about it here.

Click images to enlarge.

Tokens and medals can also be Double Struck, like this 1840 William Henry Harrison Campaign Medal. Like the ancient coin, this one is Double Struck with Rotation, meaning it was re-oriented at a different angle before being struck again by the dies. A faint version of the obelisk on the obverse can be seen slightly angled amid the stronger second strike. There are also ghostly letters from the earlier strike, including an R below the word FAIR and an S to the left of SEPT. Faint reminders of the characters in BUNKER HILL and 17 JUNE 1775 on the reverse can also be seen. This medal is offered in another Heritage Auctions sale in August 2024.

Click images to enlarge.

NGC-certified Double Struck coins sold through Heritage Auctions include:

• a 1925-D Quarter Eagle graded NGC Mint Error MS 62 - Double Struck that realized $57,500 in April 2011
• a 1787 'ETLIR' Connecticut Copper graded NGC Mint Error XF 45 BN - Double Struck and pedigreed to Hanson and Partrick that realized $43,200 in November 2022
• a (1864-73) Two Cent Piece graded NGC Mint Error AU 55 BN - Double Struck, Second Strike Off Center that realized $38,400 in December 2022
• a 1799 Eagle graded NGC Mint Error MS 62 - Double Struck with Obverse Rotation that realized $35,650 in November 2004
• a 1793 Wreath, Vine and Bars Cent graded NGC Mint Error XF 45★ BN - Double Struck that realized $32,900 in January 2014
• an 1891 Quarter graded NGC Mint Error MS 62 - Double Struck, 2nd Strike Off Center that realized $31,200 in August 2020
• an 1882-CC Morgan Dollar from the GSA Hoard graded NGC Mint Error MS 62 - Double Struck that realized $29,900 in August 2006
• a Mexico 1880GA FS 8 Reales graded NGC Mint Error AU 55 - Double Struck, Second Strike Off Center that realized $24,000 in March 2023
• a Great Britain 1863 Sovereign graded NGC Mint Error MS 66 - Double Struck that realized $17,400 in August 2022
• a Great Britain 1848 Sovereign graded NGC Mint Error AU 53 - Double Struck, Second Strike Off Center that realized $6,600 in May 2022

Other Mint Error Coin Chronicles Articles:

• Broadstrikes
• Brockage
• Off-Center Strikes
• Partial Collars
• Rotated Dies Error
• Strike-through Error
• Transitional Errors
• Wrong Planchet Errors