I bought some cosmetic packs and opened them.
I changed my card back to Paper and then proceeded to purchase another four cosmetic packs.
The four cosmetic packs gave me the Paper card back, four times in a row. I opened these packs from the link from the store page, not the home page.
Out of the 10 cosmetic packs I've opened, 5 of them are the Paper card back.
Please investigate why the cosmetic packs gave the same item 5x in a row.
Edit: The cosmetic packs did give me new cosmetic items but opening the packs appears to be bugged to showing a cosmetic previously obtained.
You didn't receive the same item multiple times, it was just showing your current selected Card Back. When the Card is clicked, it will flip and show what you received from your Cosmetic Pack.