When designing a visualization tool, in order to help the users explore the data, we would allow interactions for example selection. In my case, I have the same dataset but the points are clustered by different features. Should I allow multi-selection across the various features? Even if the operation may select the same point twice or more. Should arbitrary operation from users be allowed?
I would probably say it depends on how much flexibility you want users to have. Allowing multi-selection could actually be helpful, especially if it lets users spot overlaps between clusters based on different features. This can reveal interesting patterns you might not see otherwise.
The main thing I would say is to make it clear when the same point gets selected multiple times. Maybe highlight it differently or show a small indicator, so users don’t get confused.
Personally, I would keep the interaction open, but make sure the tool gives some kind of visual feedback. Restricting users too much can limit exploration, but also total freedom without guidance can get messy fast.
Curious to see how this idea developed, if you have continued working on it since!