It’s suggested but not required that players use different sleeves for the different decks (Main, Rune).
§ 422.2.a Tournament Rules PDF (officieel)
§ 422 Sleeves
§ 422.2 If a player chooses to do this, all such sleeves must be identical and all cards in a deck must be placed in sleeves in the same manner. Cards in decks must have the same number of layers and be the same orientation at all times.
