As per the document, there is no such a field called alertresolved,
if that is a custom field, by default prefix will add i.e cf_xxxx and it should not be duplicated.
I would suggest changing one of the field names to any other name.
@Nabbs You can make a GET API for one of the tickets with a value for both the custom fields and check if there are changes in the field names.
If there’s no change in the field names, it could be the case as you have mentioned. In that case, the Freshservice portal can be ignoring the “_” character in the field names.
If you could confirm the names you see from the GET API, I could check with the Freshservice team about it and confirm.