Can I use the same time machine backup for two macs?
In a nutshell: No, you can't.

A backup is not a synchronisation solution so there is always a 1:1 relationship between your main drive(s) and your backup. You can use Time Machine to backup multiple computers to the same network drive, but the backups will always end up as separate bundles.

To transfer applications/data from one Mac to another once, have a look at Migration Assistant (/Applications/Utilities/Migration\ Assistant.app). To share data with ongoing updates from several machines, consider defining remote access/folder sharing on a master drive or look into rsync.