Apply Computer Name and local hostname with System Image Utility
Try this format:-the Order is MAC Address, hostname (fqdn or not), Computer name (optional), Bonjour name (optional)

00:2c:76:8d:28:3b -automatic- Computer 1 Computer 1
00:2c:76:8d:28:2b -automatic- Computer 2 Computer 2
00:2c:76:8d:28:1b -automatic- Computer 3 Computer 3