I know I'm coming in late to the conversation, but as Storyline still exhibits this behavior with Format Painter, I wanted to put in my 2 cents.
I strongly feel you need to change the Format Painter so it duplicates the formatting and states, including removing states that don't exist in the source object.
As it is, if I want to remove a state (or in my case, 4 states), I am forced to go into each shape, edit states, delete the unwanted states one at a time. I have about 30 buttons in my project that require this. This is almost as much work as just starting over and rebuilding the affected pages. Almost, but not quite. I feel that, as a tool, Format Painter isn't providing the function of saving me time and effort. If I was able to paste the exact formatting of one shape (including the number of states), it would save me a ton of time.
I can't see many circumstances where I WOULDN'T want it to remove states. Why would I paint states from one shape to another and expect the receiving object to retain other states? If I wanted this behavior, I would instead create two versions and use Format Painter to copy and apply the appropriate formatting as needed.
In other words, as it's currently designed, it's much less useful than it should be, and seems to be accommodating a workflow that doesn't match my real-world needs.
As it is, I'm going back to my project and painstakingly removing states from dozens of shapes, wishing I had a better way to do this.
Seth