In case duplicate TAN has been allotted, which TAN should be used?
In case duplicate TAN(s) have been allotted to a person, then the TAN which has been used regularly should be used. The other TAN(s) should be surrendered for cancellation by using "Form for Changes or Correction in TAN" which can be downloaded from the website of NSDL ( https://www.tin-nsdl.com ).​