Coin Alterations
Even with many fail-safes and quality control checks in place, mints aren't perfect, as you might imagine by the many error types just described. But sometimes, mints are able to fix their mistakes by altering the coins. These coins are called alterations. For example, when a letter in the legends on a coin, a mint mark, or the date is impressed incorrectly into a coinage die, a mint engraver may repunch that letter or numeral over that mistake to make a correction.
If you think about it, any alterations are technically errors, but coin collectors treat them as desirable varieties within a series rather than as error coins. Many date and mint mark sets of particular U.S. coin denominations are not considered to be complete unless the “overdates” are included. As an example, the Standing Liberty quarter series of 1916 to 1930 includes a 1918-S quarter in which the coinage die originally carried the date 1917. Since no one at the mint wanted to have to destroy a perfectly good unused die, the last digit was simply repunched into the die so it could be used to mint coins during 1918. This is expressed as “1918/7-S” in coinage vernacular. This overdate variety sells for many times more than does the normal 1918-S quarter.
Repunches and Overdates to Look For
There have been many repunched and overdated U.S. coin variations since U.S. coinage began in 1793, however a casual collector has a much better opportunity to encounter such variations struck during the twentieth and twenty-first centuries than from earlier periods. If you'd like to identify all the overdates and repunches in the entire U. S. coinage series, check out a coin catalog on the subject.
Here are some repunches and overdates that you might find in family collections and accumulations:
| Repunch or Overdate | What to Look For |
| 1909-S Over Horizontal S Lincoln Cent | The mint mark appearing below the date was initially added sideways to a coinage die, then corrected. |
| 1922 No Mint Mark Lincoln Cent | Excessive die polishing wore the mint mark (appearing below the date) off three coinage dies to varying extents. Varieties of this coin exist with only a partial or no mint mark as well as the normal 1922-D coin. The most valuable variety is that in which the mint mark is entirely missing. Beware of counterfeits. |
| 1922-D | Cents where the mint mark has been artificially removed. |
| 1943-D/D Lincoln Cent | The mint mark appearing below the date was punched twice onto the coinage die from which this variety was made. |
| 1944-D/S Lincoln Cent | The wrong mint mark was added to a working die, followed by repunching the correct mint mark over it. |
| 1946-S/D Lincoln Cent | Once again the wrong mint mark was first punched into a working coinage die, followed by an easy-to-see correction. |
| 1914/3 Buffalo Nickel | During 1914 a 1913 coinage die was used, with the digit 4 punched prominently over the 3. |
| 1918/7-D Buffalo Nickel | The lower portion of the 7 weaves through the lower loop of the 8 on this interesting repunch. The mint mark appears below the denomination on the reverse. This is an expensive coin. |
| 1937-D Three-Legged Buffalo Nickel | This is an almost legendary error in coin collecting. The front leg was accidentally polished off a working coinage die. Be aware of counterfeits! Genuine examples show a stream of raised dots between the buffalo's belly and the ground. |
| 1938-D/S Buffalo Nickel | You'll need to look closely at the mint mark below the denomination to find this variety. The S mint mark is very light, while the D is bold. |
| 1942-D/Horizontal D Jefferson Nickel | This is the copper-nickel variety nickel of this year, not the “war” nickel with silver content. The mint mark was first punched sideways into the working die. The mint mark appears at the right side of Monticello on the reverse. |
| 1943/2-P Jefferson Nickel | This is not a well-known variety and can be seen only under strong magnification since the underlying 2 is not well defined. |
| 1949-D/S Jefferson Nickel | It is unusual to find a mid to late twentieth-century repunched U.S. coin. Use magnification to examine this mint mark. This is a coin that might still be found in circulation. |
| 1954-S/D Jefferson Nickel | The lower loop of the S will appear to be doubled under close examination, but it is actually part of the underlying D you will see. |
| 1955-D/S Jefferson Nickel | Watch for what appears to be a doubling to the top of the D. It is actually part of the underlying S. |
| 1942/1 Mercury Dime | The date will appear to read “19412” on this grossly messed up overdate. Someone was particularly careless at the mint when correcting a 1941-dated coinage die for use during 1942. |
| 1942/1-D Mercury Dime | This is the only case in U.S. coinage history in which two mints struck overdated coins of the same denomination in the same year. The 4 will appear to have an extra lower leg on this overdate. |
| 1950-S/D Roosevelt Dime | Although several doubled die coins exist within the Roosevelt dime series, this is the only repunched mint mark. Unlike on modern nonsilver composition Roosevelt dimes struck beginning in 1965, the mint mark appears at the left of the lower portion of the torch on this coin. |
| 1918/7-D Standing Liberty Quarter | This is a very popular coin since it is the only overdate in this particular series. The 7 appears to run right through the loops of the 8 on high grade examples. |
| 1950-D/S Washington Quarter | Close examination is necessary to see the underlying repunched mint mark on this variety. |
| 1950-S/D Washington Quarter | Whoever added mint mark punches to the working coinage dies for this coin made a mistake twice, as there is both a D over S and an S over D variety to collect. Once again, magnification should be used when looking for this variety. |
| 1900-O/CC Morgan Silver Dollar | This is the only such twentieth century or twenty-first century repunch found on any dollar coin. Leftover Carson City Mint reverse dies from 1893 (1893 is the final year in which silver dollars were struck in Carson City) had been shipped to New Orleans for use, but the old mint mark was not entirely effaced. A shadow of the original CC mint mark appears below the O. |
| 1901/0-S Coronet $5 Gold Half Eagle | Repunching and overdate varieties are extremely rare in the U.S. gold coin series. Ironically this overdate does not command much of a premium value over that of the normal 1901-S coin. |
| 1909/8 Saint Gaudens $20 Gold Double Eagle | The only way to see the underlying 8 on this coin is by examining the area of the lower hook of the overlying 9. |
Mules
In coin collecting terminology, a mule is when two mismatched dies were used to strike a coin. An example would be a 1-cent coinage obverse with a 5-cent coin reverse, although this has never happened. Collectors should be aware that obverse and reverse dies mount differently into mint coinage striking machines. For this reason it would be easy to determine if two obverse or two reverse dies had improperly been set up together. In other words, there is no such thing as a “two-headed” coin.
A U.S. “mule” coin has in fact been legitimately minted. The so-called “transition” 1859 and 1860 half dimes and 1859 dime lack the legend “United States of America.” The variety of 1856 to 1859 carries this legend on the reverse, while the variety of 1860 to 1873 transferred it to the obverse. Because of mismatching the dies, this legend is missing from each of these mint mistakes.
In fact, two-headed coins are occasionally found in circulation. These are novelty or magician pieces produced outside the mint as trick coins. Either two coins have been cut in half and fixed together (in which case a tell-tale groove will appear on the edge) or one side of a host coin has been carefully machined out inside the grooved edge, with the complementary side of a second coin carefully machined to fit into this void. Close examination of the inner side of the raised edge of a coin will reveal a tiny gap in such a nicely made piece.
Two-headed fantasy pieces are typically available through novelty mail order catalogs. The coins occasionally enter circulation, where noncollectors often mistake them for being fantastic rarities.
