When in doubt, search the TDA blog.
In our house, a fouled deck is a voided hand. Reconstruct the pot and return monies to all players in the hand.
Irregularities 3: If a card with a different color back appears during a hand, all action is void and all chips in the pot are returned to the respective bettors. If a card with a different color back is discovered in the stub, all action stands.
So, if cards from the wrong deck played, then kill and return. If cards from the wrong deck are in the stub, but not played, action stands, per above.
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p.s. Marky Mark is the best dedicated dealer around (Tony's friend, Sam, is great too). I love it when there is a dedicated dealer! Tip your dealer well! (Foster, I owe you.) :D