The DMCA is deliberately designed to discourage recipients of takedown notices for doing any verification beyond that the notices ate in the correct form before complying, since the safe harbor only applies when a proper (in form) notice is complied with and there is expressly no liability that can attach for complying with a formally correct notice that is substantively incorrect.
So I'd assume any due diligence is directed at formal correctness rather than substance as any other approach would have added cost to implement while increasing legal risk.
So I'd assume any due diligence is directed at formal correctness rather than substance as any other approach would have added cost to implement while increasing legal risk.