If it matters to you, according to the office of national statistics Amelia was the most popular girls name last year, and Mia was number 10. So eaither way there's likely to be a few of them in their school year!
No I'm not bothered by knowing other Amelia's that's likely to happen whatever the name unless you choose something pretty obscure. Maybe I'm overthinking it just meant it might feel a little weird when the we announce the name and the person I sit next to is like oh she's named her after me lol but yeah it's probably not an issue and I can see half of you thinking what is she going on about
I have an Amelia, she's nearly 14 and there are no other Amelia's in her school of nearly 1000 pupils. She used to be Mimi as a toddler but now doesn't use a nickname. I still love her name, picked it out when I was a child myself!