I don't understand what you're saying. The law of conservation of expected evidence applies only to expectations of evidence and is conditional upon your current level of belief.

It seems to me that your possibility that "what you're describing as many reasons is really a set of different manifestations of the same underlying reason" is exactly the point at issue. The underlying reason is that something is true. I can think of many reasons to believe Russia exists. I've seen pictures of it, I know people who have been there, I've read literature by Russian writers, et cetera. I know of no evidence that Russia does not exist. I can think of more reasons to believe Russia exists than that Russia does not exist because Russia exists. Likewise, I can think of many more reasons not to kill a policeman than I can think of reasons to kill a policeman, and this is because killing a policeman is a bad idea.

Am I missing your point?