La ejecución de InstancePersistenceCommand se interrumpió por una colisión de claves. La clave de instancia con el valor 'Y' no se puede asociar a la instancia 'X' porque ya está asociada a otra instancia, 'Z'.
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English version
The execution of an InstancePersistenceCommand was interrupted by a key collision. The instance key with value 'Y' could not be associated to instance 'X' because it is already associated to a different instance, 'Z'.