Cannot insert duplicate key row in object with unique index . The duplicate key value

Cannot insert duplicate key row in object with unique index . The duplicate key value

  

I am new to Outsystems and SQL. I am try to create a Bus Application where the entities are enter image description here

When I try to create a new rider with the same name and different Route and bus Id. I get
Cannot insert duplicate key row in object 'dbo.OSUSR_6SL_RIDER' with unique index 'OSIDX_OSUSR_6SL_RIDER_4NAME'. The duplicate key value is (ABC). The statement has been terminated.
When I check Name field in the database table 'dbo.OSUSR_6SL_RIDER' it is not having the unique identifier set up. Can anybody please help me with this.

Well v, it would help if you show the indexes you do have of the Rider table.