Creating a Master image OSX
When creating a master image from a mac computer, you have to be sure to delete the following files. This is will remove all the unique values from the master computer and be recreated when it the imaged computer first boots up.
You can boot the computer into single user mode see article http://support.apple.com/en-us/HT201573.
rm -rf /Volumes/Macintosh HD/System/Library/Caches/*
rm -rf /Volumes/Macintosh HD/Library/Caches/*
rm -rf /Volumes/Macintosh HD/Library/Preferences/OpenDirectory/Configurations/Active Directory
rm -rf /Volumes/Macintosh HD/Library/Preferences/OpenDirectory/Configurations/LDAPv3
rm -rf /Volumes/Macintosh HD/Library/Preferences/OpenDirectory/DynamicData/Active Directory
rm -rf /Volumes/Macintosh HD/Library/Preferences/OpenDirectory/DynamicData/LDAPv3
rm -rf /Volumes/Macintosh HD/Library/Managed Preferences/*
rm -rf /Volumes/Macintosh HD/private/var/db/volinfo.database
rm -rf /Volumes/Macintosh HD/private/var/vm/swapfile
rm -rf /Volumes/Macintosh HD/private/var/vm/sleepimage
rm -rf /Volumes/Macintosh HD/private/tmp/
rm -rf /Volumes/Macintosh HD/private/var/tmp/
rm -rf /Volumes/Macintosh HD/private/var/run/*
rm -rf /Volumes/Macintosh HD/private/var/db/.configureLocalKDC
rm -rf /Volumes/Macintosh HD/var/db/krb5kdc
rm -rf /Volumes/Macintosh HD/etc/krb5.keytab
rm -rf /Volumes/Macintosh HD/Library/Keychains/System.keychain