I don't have dogs but I do keep my cats collared and tagged. Because cats can lose collars, I keep backups, so if one comes home without their collar, I put another on right then.

I just put my last name and phone number on the collars now because I can't keep up with all the different names. (I once brought Sid to the vet and his nametag said "Joxer" and the vet tech looked very confused - like I didn't know the names of my own cats!