The same letter doesn't really bother me so much, just because it could be a coincidence. If it was done on purpose, it is a bit whatever. Not my style, but as long as it isn't too matchy it is to each their own. I would just use whatever two names I loved the most, regardless of what letter they start with. I couldn't stand the thought of missing out on using a favorite name because I had wanted my twins to be matching.
For example, for a long time my favorite boy and girl names were
Connor and
Caoimhe. I would have used that for twins had I had them at the time.