To add to what Jabberie said, if you're going to multibox and you've got room for additional accounts on your BNet account, then you should really take advantage of Recruit-a-Friend, which gives a handful of benefits that are hard to pass up.

You can have Blizzard remove the Starter Edition that is probably no longer able to receive an invite (seeing as you don't know where it came from or when it got there). No reason to confuse yourself by leaving dormant Starter Editions on your main BNet account.