Is it normal if i find it annoying my sister and i are almost the alike?

We're not twins, we're three years apart and she's the older one. But I find it kind of irritating that me and her are almost exactly the same. Not only personality wise but physically too. I started getting irritated about this when I started dating my bf. When he finally met my family, he said that my sister has the same character as me and when he looked or talked to her, he thought of me. Idk if its jealousy or insecurity but for sure I'm concerned that if he is dating me its cause he likes me (duh I kno) but that means if my sister is the same as me, he's gonna end up crushing on her too?? Maybe I'm a little paranoid but what doesn't help is he is actually two years older than her. So he's 5 yrs older than me. So they're more around each other's age where they have more in common. From their style to their taste, they have a lot of things in common. Idk if I should start acting different but I know thats just ridiculous. She has a bf but it seems like my man and her have more in common than she does with her bf. So ever since, I've been finding it annoying that me and her are almost alike. Actually, this has always been a problem but my bf has officially made it a frustration. It would get on our nerves when one got the same style as the other and would be accused of "copying" each other you know sister stuff...but yeah this whole my bf and her and me being alike is trippin me out and I don't like it. Plus there are things he wishes I was more of and my sister might have those traits he's asking of me. Then I think of some things that make me and him compatible and can never see my sister being compatible with him like that. But who knows, I def don't want to deal with awkward drama in the future. I sometimes feel like breaking up with him so I can avoid everything.