This story was a bit weird, main characters seemed to take it a bit too strongly that arithmetic failed.

I mean, there is some sense in which 1 does not equal 2. Even if arithmetic fails to define a framework where they're separate, that would simply mean that we need to redefine stuff, figure out a better way to describe our intuitive way of understanding how they're different, and thus changing the framework towards that intuitive understanding.

It would of course be a bit embarrassing, when much of the work had to be revisited and all that sort of stuff. But the characters seemed to be plain overreacting.