The correct term is "Doubled," not "Double."

Numismatists whom I respect say that

1) the proper term for the phenomenon under discussion is "doubled" die, not double die, and

2) at least in the 20th century, the overdated 1918/7-D nickel, the 1943/2-P nickel, both 1942/1 dimes, and the 1918/7-S quarter overdates can also be considered as "doubled" dies. These coins were twice hubbed, once with each date in question. Especially on the dimes, the date numerals show the telltale shift of a slight rotation from the first hubbing to the second, being just slightly out of register. Thus, these overdates can also be considered as "doubled" dies.

Dick Johnson should be aware that "doubled die," not "double die," is the settled usage among variety and error specialists and has been since the 1970s. As for PCGS usage, the glossary on the PCGS Web site says under the entry for "double(d) die": "PCGS uses doubled die as the designation."

Alan Herbert, who often labels terms that have simply fallen out of favor "obsolete," states that the form "double die" is instead flat-out "incorrect" because, taken literally, it would mean that a coin was struck by two dies. The point is that the coin shows doubling that is present on the die that struck it; hence, "doubled die." Today, a collector or dealer who uses the form "double die" is taken as inexpert.