The “duplicate key for a unique index” message with error code 107 is returned from the server when the request is trying to add an item with an Id while there is an item with the same Id in the database. This is due to the fact that the Id field must be unique. To solve this consider either:
1. Do not enter an Id when creating the item(s). The Id will be populated automatically by the system.
2. If you want to have your own custom ID for each item, make sure each one is unique.
Let me know if this helps.