No, it really does give you an advantage. When you and your opponent are using different sleeves you can know whether the cards he is holding came from your deck or his, this is an extra information can give you an advantage.
If your opponent is using cards like Night Prowler, Gravedigger's Cloak, Procured and Restored, then you have an advantage from knowing the origin of the cards in his hand while he does not have this advantage.
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