that's right. 9 times out of 10 white phoenix are covering duckwing, usually silver, but can be any of them. So yes you would get more back, they'd just be split for rec white. So when you breed these new chicks together you will get solid whites again along with more duckwings.
only exception on whites would be the very rare case that you got dominate whites, which I highly doubt you will.
only exception on whites would be the very rare case that you got dominate whites, which I highly doubt you will.