I know how you feel. I have a sister, but we're not twins. We're 8 years apart.

She likes to buy the same things as I do, then tells me I'm copying her, or she'll say something along the lines of "I look better in them anyway". For example, I'll buy a pair of Converses, and a month later, she'll do the same. Then when she sees my Converses, "yeah I hate that color", even though they're the classic black&white. Clearly she copied me, though... The she has the audacity to imply "yeah well.., mine are better!"

I tell her that she's stupid. Then she basically cries.

Oh and another thing... If I buy something that SHE wants, she goes ballistic. "WHY DID YOU BUY THAT? YOU KNOW I WANTED THAT." First of all, she NEVER tells me what she does and doesn't want to buy. Whenever I do ask her, she says "none of your business". So, she thinks I'm trying to copy her! What a load of horseshit!

Tell me about it.

Siblings are a pain in the ass, aren't they?

You could try copying her to piss her off. Basically, give her a taste of her own medicine. It pisses off my sister when I do that, and the funny thing is, I don't even do it on purpose