Violation of UNIQUE KEY constraint cannot insert duplicate key in object but there are no duplicates

Question

I have a problem, when inserting information in a table it brings back an error that already exists in the table. The problem is that the data don't exist in the destination table. This is my insert:

INSERT INTO RequisitoPeriodoPersona (PersonaId,RequisitoId,PeriodoId,PeriodoEvaluacionId,FechaValidez,Evaluacion,Observaciones) 
SELECT 
        RPPT.PersonaId, RPPT.RequisitoId, RPPT.PeriodoId, RPPT.PeriodoEvaluacionId, RPPT.FechaValidez, RPPT.Evaluacion, RPPT.Observaciones 
from 
        REQUISITO_PERSONA_PERIODO AS RPPT
            LEFT JOIN RequisitoPeriodoPersona AS RPP on 
                RPP.PersonaId = RPPT.personaid AND
                RPP.RequisitoId = RPPT.requisitoid AND
                RPP.PeriodoId = RPPT.periodoid AND
                RPP.PeriodoEvaluacionId = RPPT.periodoevaluacionid
where
        RPP.Id IS NULL

And the error is:

Violation of UNIQUE KEY constraint 'uc_RequisitoPeriodoPersonaID'. Cannot insert duplicate key in object 'dbo.RequisitoPeriodoPersona'. The duplicate key value is (1144847, 378, 133, 133). 

But when i look for this (1144847, 378, 133, 133) it doesn't exist in the table RequisitoPeriodoPersona

The table RequisitoPeriodoPersona it has a constraint with: PersonaId,RequisitoId,PeriodoId,PeriodoEvaluacionId

Do you have any idea how to solve this error?. Thanks in advance

P.S.: Sorry for my English, I'm writing from Argentina.

Answer 1

等待大神答复