A dealer friend of mine asked me to help him verify attribution and pick candidates for grading from a hoard of 20+ rolls of early 70's doubled die Lincolns he purchased. These were in rolls marked as die 2... after the first one, they kept coming, for a total of 11 die 4's. For those who are unaware, die 4 developed rim cuds soon after being put into the press and deteriorated, making it necessary to replace the die after striking a very small number of coins. For this reason, die 4 is the rarest and most desirable of the 1972 DDO's, though I must admit it isn't anywhere near as spectacular as die 1. Here is a shot of the obverse of die 4: Note the rim cuds to the left of 'LIBERTY'. They aren't found on all specimens, but are a definite marker for identifying the die 4 if present. Also note the strike-thru below the 2 in the date. Again, not found on all (8 of the 11 I found had it) but another good marker. The reverse of die 4 is also distinctive, showing heavy horizontal die polish over the entire surface: This reverse continued to be used after the DDO was replaced, and coins that have it are collectible as well.
It appears you made good choices; thank you for sharing the cool die variety. I just received the Cherrypicker's for Christmas and am starting to look for these varieties (and am always looking for error coins).
There are major doubled dies found on every year from 1969 to 1974 on at least one denomination. Someone at the mint wasn't very good at hubbing dies...
