Why does my friend copy me?

Lets say my friends name is Sally...First of all i dont want an answer saying: "she admires you" because i know thats not the case! Im goin to give examples of when she has coppied me. One time was when i got an 8gb Ipod Touch then a couple weeks later she got a 64gb iTouch!! I feel like she has to be one step ahead of me! Another example is when my mom got me and my brother herbit crabs for our birthday and then 1 week later Sallys mom bought her hermit crabs! I feel like they're family always tries to be better than our family! its like a competition between out families! Even her mom tries to make her daughter better than me! Another example is when they're family invited our family to they're house for dinner and we decided to make special brownie to bring for desert. the drownies had peppermint sticks sprinkled into the brownies so it would tast extra good! but when we took it out of the oven the brownies didnt look very good...but tasted amazing!! so when we got there everyone said it tasted amazing! then the VERY NEXT DAY her mom came over with a small plate of brownies. and get this...they had peppermint sticks it them!! but the brownies she made looked ALOT better than the ones we made...it was like she was trying to tell us: "Haha! im better than you because i can make brownies that tast just as good as yours but look better" ...another example is when i bought my first lulu-lemon jacket and pants. then when i wore then to school the first time she kept on talking about how she realy wants a lulu-lemon jacket and pants. then guess what?? next week she came to school with lulu-lemon pants and jacket!! the exact same thing happen when i got my first pair of UGGS and Juicy jacket. Also, when i got a facebook....SHE GOT A FACEBOOK 2 DAYS LATER!! another example is when my brother and i both got a hamster and we invited Sally over after school to see them and the first thing she said to her mom after she saw them was: "Mom, i want a hamster." then that very day they visited the pet store and looked at hamsters! but they didnt but one...it was a close call. i have one more example. My mom and her mom were talking one the phone one day and her mom made my mom promise not to buy me a phone yet and that me and Sally should buy them together because if one of them got a phone before the other...the other one would be jelous. so my mom promised....but the next weekend when we were out of town they went off and bought Sally a phone!! what happened to the promise?! its like she didnt care if i was jelous as long as her own daughter wasnt the one that would be jelous. So i feel like they're family has to always be better than my family...ive benn trying to not tell her about any of the things i buy because i know she would go out and buy it before i do...so plz help me!!!