I've seen this happen before and am rather disturbed by it. I've also seen it where one angry divorced parent won't let their child keep any gifts from their other parent.
I can understand if one parent buys something in particular for the girls to play with while they're at the house so that they have something to do, particularly if they've complained about being bored when they come to visit. But generally when you get a child "a gift", why wouldn't you let it be theirs to do with as they like.
Am I spoiling my daughter by thinking that she "needs" these things or do I have a right to feel sad for her?
You do have a right to feel sad for her. It's probably not just about the toys - the toys that can't be brought to mom's and have to stay at daddy's. That sort of thing really drives the point home to a kid that their parents are separate and that they have two homes, not one, and their lives are now divided. That's a hard thing to get used to at any age. As a kid you don't know how much it is affecting you. Does your daughter "need" replacement toys to have something comparable at home A and home B? Not really. It might be a kind and possibly heart warming gesture but it can also turn into a greed fest for a kid who later decides to play their parents off each other to get more stuff.
That's something I can't really answer more definitively than that.