I saw this as the best place to post this I guess, move if it isn't
Last night I got my DK to 60, and I went on my 55 warrior to send him all my gold so I could buy my flying mount, I purchased it and logged off for about 15 minutes. I log back on my DK and I have the 200g I sent him, I know for a fact I only had 16 gold left after I purchased the training + mount.
I was currently still downloading the game, and had connection problems around 15 minutes before I sent everything, I don't know if this caused me to dupe this 200g.