1991 Topps Baseball Forum

I was browsing these on eBay thinking of adding some hard to find royals cards but had a question about the backs of the cards. Many of them at eBay have the Dessert Shield stamp on the front but the backs vary. Some have the normal back, some have the dark logo, some have a white back. Are many of these counterfeit? I want to make sure I’m getting something legit but it’s hard because Topps had several variations of the backs of cards for this set.