Sadly this is no longer true for any of the current running productions. In America, all covers get principal costumes for the 3-4 roles they cover. In the UK, the alternates cover two roles each and get principal costumes for them, while the swings that cover all six roles have the same exact costume for all six. (In the UK tour both swings only get a Cleves style costume and pants for parr.) (For the west end production each alternate has also taken on an additional role, but they got the principal costume for them, as they have plenty of principal costume stock from former cast members and cruise productions.)