Welcome to an ongoing educational series designed to help the beginning variety collector as well as the seasoned professional learn more about the various forms of doubling that imitate the distinguishing characteristics of true hub doubling. Each month's topic will illustrate in depth how to recognize the true hub doubling such as Doubled Dies (DDOs/DDRs), RePunched Mint marks (RPMs), Over Mint marks (OMMs), MisPlaced Dates (MPDs), and RePunched Dates (RPDs) as compared to other forms of doubling.
This month we will take a look at the major differences between Mechanical Doubling Damage (MDD) compared to true hub doubling as illustrated with a doubled die reverse (DDR) Lincoln cent. Mechanical Doubling Damage (MDD) is also called machine doubling, strike doubling, shelf doubling, ejection doubling, and chatter doubling, just to name a few. Actually, it doesn't matter which one of these terms you decide to use, as long as we are both talking about the same thing. For the sake of simplicity, this article will utilize the term mechanical doubling. The major point is that mechanical doubling is very common on modern-day coinage, and can easily be confused with true hub doubling.
For most die variety collectors just starting out in our great hobby, the most difficult part is understanding what constitutes the real doubled die as compared to mechanical doubling. Even the professionals occasionally get tripped up on this form of doubling that closely mimics a true doubled die. Before we get started, let me make one point. The correct terminology for a doubled die is "Doubled Die," NOT a "Double Die!" The die itself is doubled and hence past tense. The term "double die" is NOT past tense and is incorrect terminology.
As the old adage goes, "A picture is worth a thousand words," and the easiest way to learn the differences is to compare photos of mechanical doubling with photos of a doubled die reverse. Photo #1 depicts mechanical doubling on the letters "STATES OF" from a 1996 Lincoln cent reverse that was simply pulled out of pocket change.
Notice that the mechanical doubling has a flat, shelf like appearance. Hence one of the terms as "Shelf Doubling." There is NO notching on the lower or upper serifs or any separation/division lines. However, at first glance, this photo of a Lincoln cent reverse gives the impression that it's a doubled die!
Now lets take a look at Photo #2. This photo was taken from the doubled die reverse 1964 Lincoln cent 1-R-I FS#1c-026 at the SAME magnification and framing as Photo #1.
Here we see the distinctive notching and separation/division lines that are major characteristics of true hub doubling. The letters "STATES OF" and "EPU" also are thicker from the counter-clockwise (CCW) shift between the first hubbing of the die to the second hubbing impression. Another key point between the two photos is that in Photo #1 the mechanical doubling is not evident on "EPU," but the true doubled die reverse in Photo #2 is evident on all the lettering. Also the mechanical doubling only affects the upper half of the lettering "STATES OF," while in Photo #2 the hub doubling affects the total letters.
In our next illustration, Photo #3 is magnified to 35x power. Again, this is the 1996 Lincoln cent reverse with mechanical doubling damage.
Here we can readily see that there is NO notching of the serifs and the trademark flat, shelf-like appearance of mechanical doubling. Comparing with Photo #4, also magnified 35x power, one can observe the distinct notching on the upper and lower serifs of the "S" of "STATES" and the separation/division lines on all the lettering. This lettering also has the rounded shape characteristic of true hub doubling as compared to the flat shape of mechanical doubling damage.
Finally, we compare with the lettering "AMERICA" and once again the flat, shelf-like appearance is visible in Photo #5.
With Photo #6 the same magnification and framing illustrates the true hub doubling characteristics. The distinctive notching and separation/division lines are once again visible along with parts of the Memorial building. Also note that there is NO doubling visible on the Memorial building in Photo #5!
Learning to recognize the differences between true hub doubling and mechanical doubling damage is probably the most difficult for the die variety collector. I have seen many numismatic press advertisements selling mechanical doubling coins at very high prices that normally should be in the .50c to $1.00 price range. This happened quite frequently when the 1995 Lincoln cent DDO-001 hit the die variety community. I will point out that even dealers get confused between the two types of doubling and more often than not, unintentionally misrepresent in their advertisements.
There are a few who only collect mechanical doubling coins. There is nothing wrong with this, as long as you know the differences between mechanical doubling and hub doubling. The bottom line is to collect what you want to collect. I have seen some examples of mechanical doubling that are very impressive and my personal collection contains a few specimens that nicely illustrate the differences.
Photos #7 and #8 below are probably the most classic examples of mechanical doubling damage (MDD). This is the 1969-S 1c (MDD) that perfectly illustrates the trademark flat, shelf-like appearance that mimics hub doubling on the date, Mint mark, and LIBERTY. Notice in Photo #7 that the Mint mark also exhibits mechanical doubling. During this production period of Lincoln cents, the Mint mark was hand-punched into the working die after the annealing/hubbing process was completed. If this were a true doubled die, then the Mint mark WOULD NOT show any doubling whatsoever. This is a "red flag" that is a sure indicator of mechanical doubling. It is this mechanical doubling that can be easily confused with the true doubled die obverse (DDO) 1969-S 1c WDDO-001 FS#1c-028. That doubled die Lincoln cent is extremely rare and can command a significant premium upwards in the thousands of dollars depending on grade and condition.
Nearly every coin show that I have attended, someone comes up and proudly shows me a coin just purchased or cherrypicked believing it is a doubled die! Unfortunately, most times the coin was only mechanical doubling damage. I specifically remember one case when the coin was annotated as a "Doubled Die" in an encapsulated holder by a major grading service, yet it was only mechanical doubling! It is always difficult to try and explain to the excited collector that he/she doesn't have a true doubled die! Though mechanical doubling can show up on any denomination, it is most prevalent on Lincoln cents (especially the reverse) and Jefferson nickels.
For the beginning collector, learning the major differences between mechanical doubling and true hub doubling is difficult at first, but in the long run, will save you a lot of heartaches and frustration as you build your die variety collection. If you have any questions about mechanical doubling or comments about this article, I can be reached at: P.O. Box 50428, Summerville, SC, 29485-0428 or E-Mail: Billy G. Crawford. Next month, in Series #2 of NCADD's exclusive "Educational Series on Die Doubling," we will take an in depth look at Die Deterioration Doubling vs. Hub Doubling.
(All microphotographs done by Billy G. Crawford)