The past few days I've been trying to solve a mystery.

I've run a disability chat room for 17 years now and the whole time we
have had our own custom chat client that connects to a customized
ircd.  For the identd portion of the connect, I have always used an 8
digit random number but as of v3 of the client, I seeded the random
number generator with their MAC address so their identd would be the
same if they re-installed.  I have always been under the impression
that no two devices would ever share the same MAC.  Note that this
isn't a security issue for the site, it's just a convenience thing for
me.

In the last couple of months, 4 people have come in with duplicate
id's.  This has never happened before.  Finally today a new guy came
in and he turned out to be a programmer too so we talked about it and
he gave me his pc's mac address.  58-2c-80-13-92-63. On a whim, I
googled it and holy crap!

I'm going to switch algorithms but I'm still curious, is it normal for
vendors to recycle MAC addresses?

Daniel