To answer your question, Ammo-Lock will work like a dechlorinator. If you've already spent your money on it, I think it would be ok to go ahead and use it as your dechlorinator. Although, usually I think it's best to not add extra stuff to your tank, if there's no need, and the Ammo-Lock will add an ammonia blocker that you don't really need. As other people have said, the amount of ammonia released when the chloramine bond is broken is negligible.
Keep in mind, too, that Ammo-Lock can affect the readings on ammonia tests. If you're having an ammonia spike, the tests will still read the ammonia level as being high, even if the Ammo-Lock has neutralized it. This is the case for tests that do not distinguish between NH3 and NH4+.