multiple machines-different preferences-one account

I have multiple machines available and now have two running. It doesn't seem like I can have different preferences for the different machines without creating multiple accounts since the preferences live on the server instead of locally, or am I just seeing this incorrectly? I would like to run a couple of machines flat out on the project, and at least one machine only about 25%. Disk sizes are all different, and cpus etc. so on two of the machines I'll run only when idle . . .

How do I set up different preferences for different machines all under one email account?

Thanks