DBAPIError while inserting scenario_alternative items

[amnanni]

Over the past week two days I've had this problem happening multiple times: While creating scenarios by clicking the alternatives and then committing, I get error

"From Input_data:
DBAPIError while inserting scenario_alternative items: ('UNIQUE constraint failed: scenario_alternative.scenario_id, scenario_alternative.rank',)".

It happened to me with two different models, and one I was able to fix by creating a new scenario (with the exact same alternatives), but this did not work for my other model as I still kept getting the same error.