CF table: possible to add same biosphere flow twice

Updating AB

[X] Yes, I have updated AB and still experience this issue

What happened?

It's possible to add the same flow as CF to an impact category twice. This should not be possible, we should only be able to characterize a flow once.

Also, deleting the flow deletes both instances of the flow

Relevant errors

No response

Operating system

Windows 10

Conda environment