Yes, and it's not even like there was a prior plan to use two bombs and see what happened - the military was fully planning to continue the atomic bombings as the cores became available (the third expected to be available by late August). It was only Truman intervening that stopped it at two.
It seems, unsurprisingly, that the military didn't really see the atomic bombs as anything other than a really big bomb - it was only later that they came to be seen as something qualitatively different, and "a bomb so big it is war-ending" is really only something you can know in hindsight.
> It seems, unsurprisingly, that the military didn't really see the atomic bombs as anything other than a really big bomb - it was only later that they came to be seen as something qualitatively different
That, arguably, came with advances in delivery methods. A-bombs alone don't end wars. Multiple sides each putting them on advanced bombers and intercontinental missiles, made to hit quickly and be effectively impossible to stop - that's when nuclear weapons graduate from being just bigger bombs to being existential threats and/or tools for keeping world peace.
It seems, unsurprisingly, that the military didn't really see the atomic bombs as anything other than a really big bomb - it was only later that they came to be seen as something qualitatively different, and "a bomb so big it is war-ending" is really only something you can know in hindsight.