Hi,
iChat (Or Messages) with any Buddy List will display the Users ID (or Screen Name if AIM) as it is sent from the server.
It is the app that links to your Address Book (Contacts app in Mountain Lion) that provides the link to displaying the person's "Real Name"
As the info in the Buddy list changes between the regular display (either the Buddy's ID or their Name from the Address Card) and the Numbers it is a server end issue.
Furthermore it is a Security Issue as presumably these numbers are something to do with people's Facebook Accounts that is not normally public.
I don't have a Facebook account.
Is that not a Facebook forum for this sort of stuff ?
8:58 pm Friday; July 26, 2013
iMac 2.5Ghz 5i 2011 (Mountain Lion 10.8.4)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad
"Limit the Logs to the Bits above Binary Images." No, Seriously