I was working with GS Support on an issue with case statements in Rules Engine and it was determined that if you configure multiple case expressions with the same number/currency (such as ARR) in a single task, Rules Engine will use the same output from the first case expression for all other case expressions in the task. 

It was determined this was a “limitation” instead of a bug and the proposed workaround solution was to create another transform task and duplicate the number/currency field so that a unique field is used for each case.

I would argue this is not a feature limitation but a bug with case expression behavior. Please consider fixing this in a future release. The workaround works but it requires additional for admins just to use out of the box features.