Context:
Adding an already existing filter to a report usually means skipping the addition of that filter but that's not always the case. e.g. adding a running instance filter twice will only add it once. On the other hand, adding suspended twice will add the filter twice to the panel.

AT:

• Find all the filters that cannot be added twice: 
  • Instance state
  • Flow Node status
  • Incident filters
  • start date, end date
  • user task duration time for decision reports
• Adding one of those filters multiple times only result in one filter in the filters panel