I have three accounts and on all three accounts all of my items have been duplicated. Shortly before the pre-patch hit (server shutdown here was at midnight and I started at 10:30PM), I transferred all my items over to the one character on each account I was going to pay the £12 clone fee for. I made sure that nothing was left in the mail box of any character except the paid clone character. All this went well, I got a copy of all my loot on the Burning Crusade as expected.
Things got interesting when I logged in to Vanilla. What appears to have happened is all the mail I had sent to cloned character was still in the mailbox, in addition, this mail had also been returned to the characters that sent it. This means I now have a duplicate of every single item in Vanilla.
I have posted in chat and it seems (if people are being honest) that I am the only person this has happened to but I find this hard to believe if it’s happened on three accounts.
I play very casually and barely have any loot of any value. In fact, it was a bit of a pain in the rear as I had tonns of murloc eyes, vulture meat, elemental waters etc (this took ten hours to sort through). I now have two copies of Soulkeeper which is nice, I couldn’t decide whether to give it to my mage or priest, now I can have it on both. I made a full set of gear, including blues, for all my alts of every class. I now have two copies of all this levelling gear which is useful if I wanted to make another set of alts on linked realms.
@Blizzard: My mailbox on one of my accounts (except for one characters mail) is untouched and I have 27 days left on the mail, just in case you need to have a look and think I’m confused. I have gained very little from this but if I’m honest, it would have been lovely to have had a load of epics in my stores.