Turn on one machine - turn off Sharing - close System Preferences - go back in and turn sharing back on - then do a Repair Permissions - turn that machine off - do the same on the next one.
did what you said - I no longer have several versions of my iMac showing up under shared devices.
when I openned Finder this morning my iMac was listed under devices as 27" iMac (2). an hour later it is showing up as 27" iMac (4). I've no idea why it's doing this - I haven't re-booted or done anything other than a bit of browsing.
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