Indeed, I just "hacked" the vBookie hack yesterday so it would work that way. You shouldn't get the money you spent back when you win, only the odds multiplied by how much you bet. :P
The way we had it set before was that if you won you'd get the money you spent back, plus the amount you bet times the odds. That's not how real betting companies (the ones I know of) do it. The money you've spent are instead included in the odds.