Understanding 一組別の模様が浮かぶデック

Question

From Kakegurui manga ch. 2, Yumeko was challenged a game by a student council member. To summarize, the game she was challenged in is a concentration game that involves two sets of standard deck of 54 cards. Her opponent sneakily prepared a special deck where each card has different back pattern, which at glance appears no different from back pattern of ordinary cards but a trained eye can recognize a difference. This allows her to tell cards apart by looking at back pattern alone. Yumeko lost at first but was able to win the game in the second round, despite cheating involved. She won because she recognized her opponent used the same deck in the first round. She remarked that

貴方がもう一組別の模様が浮かぶデックを用意していればお手上げでしたのに

I have hard time deciphering the relative clause 一組別の模様が浮かぶデック. I initially understood it as "a deck where each card has unique back pattern." However the context demands me to understand it as something like "a deck where each card has unique back pattern different from the first round." I don't know why my initial interpretation is mistaken. 一組別 means "different for each card", no?

Answer 1

That 一組 is not part of the relative clause but a quantitative expression that adverbially modifies 準備する. It's this. 組 is a counter for decks, sets, pairs, groups, etc. The relative clause that modifies デック is only the 別の模様が浮かぶ part. It'll be easier to understand what's happening if the word order is changed like this:

貴方がもう一組別の模様が浮かぶデックを用意していれば、...
= 別の模様が浮かぶデックを、貴方がもう一組用意していれば、...

If you had prepared another deck with different (back) patterns, ...
If you had prepared another pair of decks with different (back) patterns, ...
^{(According to the comment below, this seems to be the correct interpretation)}

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一組別 means "different for each card", no?

No. 一組 ("one set/deck/pair") never refers to an individual card, so you should not come up with an interpretation that contains "each card".