ooh, you learn something new every day!
I only thought this because my friebd at uni was an Aine and she was convinced that Anya was just a bad spelling (probably because people would do that all the time)
and now that you say, Aine is more "onya" sometimes, isn't it? my Aine was liverpulian, so she said "ann-ya"
and now I know the origin of Anya, I'm putting that spelling into my preferred name.