Might have to do with creating a catalogue category via the new catalogue screen.

This bug is not fixable:

* The double submission check looks in the action logs. But the action logs do not map category to catalogue. Therefore, double submission cannot compare based on catalogue to prevent this bug.

* We also cannot do a direct database check for an existing category because titles are stored as translation IDs. This means we would have to translate every row in order to do a check to see if the title exists.

* We probably cannot use a redirect hack to prevent this bug (e.g. create the catalogue first, then redirect to another actualiser for creating the categories); this will break the do-next schema.

* Finally, we cannot simply remove the double submission check; it's the only guard we have against making categories with the same name (though a very bad one as it's still very possible to do, not that it would break anything though because they would have different IDs).

Also worth noting that this gets even more complicated when factoring in child categories.

Possibly could use set_mass_import_mode (set positive before creating category, negative afterwards, make sure double submission respects it)

Automated response: Similar submission conflict detection does not prevent creation of catalogue

When creating a new catalogue, if similar submission error is triggered, the catalogue is already created (so proceeding results in an error saying the catalogue already exists).

This fix sets mass import mode on when creating a catalogue with auto_fill categories to prevent this from happening.