Is the back identical to a regular Topps card? It's possibly a promotional card inserted into a trade magazine at the time. They were fairly common in the 90s.
Here is a sheet of 9 advertised as coming from a magazine, but the exact magazine is not listed. I recall a magazine called NBA Stuff, or something like that and it probably had cards. Don't recall if it was brand specific though.
Just looked and it was Inside Stuff. Issues had 9 card sheets included in many (all?) issues. It seems most were Fleer/Hoops cards, but maybe Topps got in some or it was from a completely different magazine all together. So much crap being pumped out in the 90s, impossible to keep it all straight.