Why would a friend accuse me of one-upping her when I don't think I do?

My friend says I "always" one-up her. I listened to her POV and asked for examples of when I one-up her, and she said it's when I say things like:

Her: You're beautiful

Me: You're beautiful inside and out, bestie!

I can see how that could be seen as one-upping by her, but I sincerely don't intend to one-up her or make her feel inferior. I was trying to give her a compliment that would make her feel good about herself. I truly meant that compliment.

How can I convince her that it's not my intention to one-up her?

Why would a friend accuse me of one-upping her when I don't think I do?
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