I believe the best term for the 1942/1 dimes is "dual-hub overdate."

These are two individual working dies that were left over from 1941 and were rehubbed with the 1942 hub. Prior overdates had only the date area affected, while these two dies had impressions from a 1941 and a 1942 hub, which had the dates on the hub. Thus, some have called these dual hub issues "double dies." Technically, they are, but as Tom Delorey pointed out, nothing is doubled but parts of the date. The 1916 double die nickel has offset impressions from a single 1916-dated hub, thus is a true double die.