why is double marker test required on What basis it is suggested

A. The term "DoubleMaker test" does not correspond to a specific medical or diagnostic test that I'm aware of. It's possible there may be a misunderstanding or a typo in the term you're referring to. If you meant to ask about a different medical test or procedure, please provide more details or clarify the name so I can offer accurate information regarding its purpose and when it might be suggested.