I have two cousins with the same name. Same side of the family, too. When we were kids it was always "big david" and "little david". It's just what we were used to.

In DH's family, there's a Simeon and his name is shortened to Sim. We get crap for having a Samuel that we call Sam... But there's nearly 6 years difference in age and our name was picked even before the older boy was born. It seems that no matter what you do with names, someone will be unhappy.

BW