Sale deed done without cancelling gpa

Sir,

Initially GPA Deed is made between Principal and Agent. After few days Sale deed is also made between the same Principal and the same Agent without cancelling the GPA.

Then the property has been sold by the Agent to other third person. Now when third person approached some bank for loan, they have asked the legal opinion and asked the third party to get the GPA cancelled from the above said Principal.

Please clarify is it mandatory to cancel the GPA? Because sale deed is made between Principal and agent themselves.

Bank says two documents should not be there for one property viz GPA and sale deed.

Please advise what the third person (who has purchased the property) should do now. And whose responsibilty is now to get the GPA cancelled.

Thanking you

Ravikumar