Something Interesting..

I've been going through my cards to make sure my lists are correct on the Trading Card Database.. Today I got to the 1990 Topps Traded and came across something interesting.. 

To illustrate, I'm going to show a Frank Wills card.. 

In fact, here's two of them side by side.. 

Not all that remarkable. Was never really that incredible a player. But it's not the player I'm looking at here.. Really it's not even the front.. 

Here's what I'm looking at... 

One card basically has the same back as the base set, while the other has the brighter stock. 

Now, on the Database, the traded backs look like the brighter stock card.. I remember in general at that time the Traded sets had a different colour back to them than the base set.. 

I just don't know why I have cards with the base set backing as well.. It's not just Wills either, I have two Wills, a Junior Noboa, Dennis Boyd, Dave Schmidt, and Bill Sampen with this style back. 

I have what amounts to two full sets with the brighter stock. 

So I guess what I'm asking is did Topps use the base stock for the Traded set in 1990 and I have Tiffany sets, or are the base stock style cards oddballs from 1990??

If anyone has information/insight/conspiracy theories, let me know!