Posted By:
AndyHCould the difference in paper stock be attributed to the fact that the coupons were printed in a different factory in Louisiana? If they were the only 'series' of T206 printed at this factory, then would it be that hard to believe that this factory might have had a different paper stock? The quality control in a single factory was somewhat low back then, let alone across different factories in different states. So couldn't one factory have secured lighter weight paper for their production of the cards?
Just a thought. Now if someone could please put me in my place and shoot down this theory I could come back down to earth. 
Thanks,
Andy
edited to add: I also think they are a separate issue but wanted to pose this question to your folks. I think the fact that they produce two other related sets in future years after T206 production stopped seals the deal as far as separate issue.