New discovery about 1956 Topps baseball cards

[Georj]

Last week I received a 1956 Topps Roy Campanella card with a cream color back. The card had a glossy feel to it on the front and back (it didn't look glossy under a bright light, just felt that way as opposed to the coarser cardboard feel that the other cards have) and was made of thinner card stock. I thought it was a reprint so I examined it under a loupe and did a black light test but saw nothing unusual. I contacted the seller about the card and he said it had been in his collection since 1974 so it could not be a reprint. I did a little experiment and went through the 300+ 1956 Topps baseball cards I have by feeling the front and back of each one. This is what I discovered. I found 7 other cards that had the same glossy feel to them and were made of thinner card stock. The cards were:
#129 Jake Martin
#170 Bill Virdon
#168 Sammy White
#142 Gene Baker
#104 Bob Lennon
#107 Eddie Matthews
#131 bob Roselli
#123 Roy McMillan
All the cards have cream colored backs. I have many cards with cream colored backs but these were the only ones that felt flossy on front and back with thinner card stock. Could these somehow be the Canadian version? Does anyone have any of these cards that the could examine to support my findings?