Ok so say I have a copy of my wallet.dat file on a USB stick and it's in my fire safe, and another copy in a TrueCrypt volume stored on Dropbox, it would not matter what version was restored? Which ever restored copy would "catch up"?
What happens if you restore it to two different PC's? Can the same wallet.dat file be in existence at the same time?
You could have as many wallets running as you want. They aren't like physical wallets, each holding their own unique coins. Your BTC wallets will refer to/point to the same coins.
You could liken it to a bank account with multiple debit cards. Each card basically allows you to spend the money in that account.