I'm trying to add an answer.db to another db. The fields are the same, but i get a keyviol. What could the issue be? (I'm using Paradox 8)

Your problem is you cannot add a new record to an existing record you have to update it. The keyviolation means that the key fields in the record you are trying to add already exists in the database. You can either delete the existing record or use the add and update process rather than a simple add.