You can boot to the 500GB drive, do a game backup in Steam, then boot into the 2TB drive and import the backup you made.
If you want even easier. You can always re-download them in Steam.
You can boot to the 500GB drive, do a game backup in Steam, then boot into the 2TB drive and import the backup you made.
If you want even easier. You can always re-download them in Steam.