I had this problem, only once, with a "friend". Whatever I did, she did. Drove me crazy! It peaked when DH bought me a new piece of something I collect. "Friend" ran out and bought the whole collection, at once, paying much higher prices then we ever did. (We'd been collecting this item for over ten years at that point, and had only known friend for a year.)
I was put in a position to influence where "friend" and her family lived, and I used it to recommend they be sent across the country. (It was time for them to move anyway, so why not?) They moved, we waved goodbye, and I've never looked back since. I don't know if "friend" ever figured anything out, I truly don't care.
Now, with all my other friends, it's okay to share what we've got, done, etc. We don't try to one-up each other, we share how the kidlets are doing, etc. They've got their style, I've got mine.
I think that's part of Cheryl's problem. She has no style, no sense of self-worth. Such a pity.