Random choice between the names, tbh, because I'm not quite sure who they even are. Are they a pair of twin sisters in Slytherin?

They were characters that were only in the movies. Their last names are Carrow and so people speculate that they are children of Alecto and Amycus.

Weren't Alecto and Amycus siblings? I'm sure one calls the other brother or sister in the final book.

^Yep they're siblings, Neville referred as such when he was explaining what happened to DaDA and Muggle Studies towards the end of the last book. Maybe these guys are daughters of one of them and nieces of the other, then (lol and you thought your family reunions were full of psychos)

@Flicker Yeah I think so that's why I was so confused when I read that theory. Personally I thought that they just so happened to share last names. But PrincesTale brings up a good point; maybe that's how it is.

Flora, she looks don't so evil like her sister