Time Machine error

I have an iMac running on OS 10.5.8 so no Cloud app. I've just bought a Macbook Pro and wanted to transfer files from the iMac to the Pro. I have an external HD with a backup of the iMac so connected that to the Pro. Unfortunately I seem to have wiped a lot of the Pro setup by doing this - the Pro now calls itself by the name that the iMac has. I've confused myself, never mind the people reading this. Does anyone know of a way I can restore my Macbook Pro to the system settings I applied at the Setup stage?