You are right about the version of Data Protector being the same, and, if possible, to have the same patch level
The easiest and safest way to move the IDB is to back it up to tape fromthe original cell manager, restore to a temporary directory on the new cell manager, stop DP and move the restored
/var/opt/omni/server/db40
directory from the temporary directory to the correct location, start DP and run
/opt/omni/sbin/omnidbutil -change_cell_name
Alternatively, you can stop DP on both systems, FTP the directory
/var/opt/omni/server/db40
to the new server in the correct location, start DP and run
/opt/omni/sbin/omnidbutil -change_cell_name