That contract only referred to the one moria pass with the shadow to become it's master, as he did with luffy, but it seems like strong memories will still remain. And well, it's never been said the shadow of the zombie cindry was that of that famous actress that died... it's only her body, and the woman who hated plate was in fact the original owner of the shadow that is animating that dead body.
Anyway, if you read back at chapters 446 and 448, hogback mentions a story about her master explaining her hatred of plates, then in the later we discover she was a famous actress on stage, and there was a hint that they were two different people when usopp asked if there was any sign that she had been a maid and nami said it didn't look like it.