Based on my research, there are three types of back for these cards: 1) blank back; 2) post card back; and 3) post card with stats back. Some but not all players appear to have multiple types of backs. See this link: https://www.worthpoint.com/worthopedia/1973-80-tcma-all-time-greats-62586480
This database has two entries for this set: this one and what appears to be a full set (1973-80 TCMA All-Time Greats Postcards) with 156 cards (same number as Beckett's checklist). Here is the link to the other set in this database: https://www.tcdb.com/Checklist.cfm/sid/84678/1973-80-TCMA-All-Time-Greats-Postcards
My vote is to have only one entry in the database for this set (the full one), delete this set, and add any VAR cards (i.e. same card different back) to the full set as we come across them.