I would think that Luca would be shortened to Luke too...Lou and Luke...cute!!

My two get shortened to Lil and Li. I think of it in terms of the future. When my kids are grown up and thier own people (not that they're not now....but I mean moved out of home, etc) I don't think they're going to be worried about the fact that their names are similar sounding. I did think about them sounding similar and getting them confused, but I don't. I get their cousins names mixed up with theirs more than I confuse their names, and their cousins are Ashley and Justin! I love their names and that's all I'm worried about now!