My friend uses me? Does she?

Ok lets call her ... Jenny. Jenny is always attached to me, although I have a best friend... Ummm Allie. Allie and I have so much history and I love her shes my best friend but Jenny is always doing everything I do and she always gets the same things I have and says the same things I do. Is she jealous of me? For example, she told me she was jealous about my trip through Europe and whenever I'm mad at someone she is too. Is this a true friend or a fake wannabe? Everyone is jealous of me allie and jenny because we've always been friends and Are inseparable. We have the best clothes and bags and everything i just want to know if Jenny is a true friend