Shit. I hadn't thought of that. I've been running Bitcoin on 2 laptops side by side from the one wallet backed up and synced with SpiderOak. I haven't had any problems yet although I was anticipating one when I initiated the sync. The second wallet was the newer one but didn't as yet have any transactions. I half expected it to become the new wallet and I would lose the old one with the transaction record and .01BTC balance. Instead, the old one got transferred to the second machine which was more than I'd hoped for. The strange thing is that on the first restart, while watching all the blocks download again with the second client, I noticed they they both had the same Bitcoin addresses on the main screen. However, since then, they have remained different but still show the same transaction records and Address Books with the exception that the newer client has 1 extra Address in its Address Book.