1973 Topps You’ll Die Laughing, new test cards?
 

I just picked up the near set of 1973 Topps YDL from Alan Miley.
Included was a lot of test set cards. These are skip numbered and the checklist is 1, 2, 3, 9, 10, 11, 12, 13, 14, 20, 21, 22, 23, 24, 25, 31, 32, and 33. The backs say collect the entire series whereas the regular backs say Collect the Series of 64 or something like that. The verbage on the test card backs is completely different also.
I’ve checked multiple sources and the numbers listed above are always consistently the same. The test set, itself, is not too rare.
Well, included are four cards, they are not OPC cards as the trademarks say Topps. But they have completely different backs but same numbers except for one of them.
These cards appear as test cards but are not listed at all on any checklist. These cards are numbers 7, 19, 26 and 30. #26 has the same front as the reg set’s #13.
Does anyone know anything about these? Are they prototypes?