The only way to find out is to try it, but most double shotguns aren't properly regulated to have both barrels shoot to the same point. This is the probably the biggest reason why double rifles are so expensive.
Incidentally, double rifles aren't regulated to have both barrels converge at a certain range, but rather to make up for the recoil which is offset from the centreline of the gun. If the barrels were parallel, the right barrel would tend to shoot to the right of the line of sight and the left barrel to the left. Likewise, an over and under would tend to shoot high and low groups from its barrels.