I've run the Ace Chemicals 2x2 with a friend twice over the last couple of days, and though we both get credit for two wins toward the "Vat Worker" feat (2/5 completed), we don't get any credit toward the "Living the Legend" feat (which just says we have to win a Legends PvP match in the Ace Chemicals map). I assume this is a bug since it doesn't say we have to run in the 4x4 Ace Chemicals mission to get credit.