If a provisional was permitted then when you find the original in bounds, the provisional is dead.
If you don't wish to plasy the original where it is then you may go back and play another ball under stroke and distance.
But MEfree was referring to a situation where a provisional was not permitted. So that when the second ball (supposedly 'provisional') was played it became the ball in play and the original was lost under the definition of lost ball (even though it was found).
Ok I think I got it. I played it legally then.