conference committee

every once in a while i'm struck by how weird the idea of conference committees are. the constitution says that the same bill has to pass both the house and senate. that sounds like you would need is single vote to pass a bill in each chamber. but instead, the two always pass different versions, then it goes to a committee that slips all this stuff in the final version of the bill, then both chambers vote a second time on the final version. you'd think there would be a better way to do this. but i can't come up with anything that would work.