Give them their own names, the two names I’d name them if I was having singletons one after the other. Twins barely have their own identity as it is, especially identical twins, without cutesy matching or even worse rhyming first names to make them even more of a matched pair.
Right now mine would be:
Avielle &
SylvieAvielle &
FranklinFranklin &
August
Even then Avielle and
Sylvie are a little similar sounding for me, I might be tempted to go with one of my other girl favourites just to avoid that - maybe
Geneva or
Xanthe or
Florence.
http://www.behindthename.com/pnl/56287