National Insurance number belongs to someone else

Bit of a weird one this, was hoping someone may have experience or advice on how to deal with it.

55+  years old African man with Indefinite Leave to Remain granted in 2005, mainly worked up to about 2011. Has numerous wage slips, letters from Inland Revenue/HMRC from 2005-11 all with his NI number on it. Also has a standard NI card with the same number on it although his name is misspelled by one letter.

He’s never claimed any benefits before, arrives at our offices destitute. We help him make a claim for UC and have to book a Biographical interview to verify his I.D. Jobcentre unable to verify his ID and say that the NI number belongs to a woman aged 25 (they probably should not have told me this but they did).

I’ve spoken to HMRC who say he cannot pass security on his NI/name etc, i.e. the NI no. does not belong to him. It also advises that as he was born abroad it is the Jobcentre’s responsibility to issue a NI number. So I suppose that the next step is to reapply for a new NI no. in order for him to be able to claim UC. Is there any reason not to do this?

Also, he is in temporary accommodation (homeless) which will be paid for by HB. It is saying to just provide proof of the NI number he has and it will process the claim but I’m not comfortable with that, am I right to worry?

What really puzzles me is how can the same NI number seemingly be issued to 2 different people? If, as Jbc say, the woman who has the number on its system is 25, she would have been 12 at the time my client started paying tax and NI in the UK and would not have had a NI number… Who knows what has happened to his NI contributions paid to date and how we can ensure these are re-credited to him for his pension, etc.

Any thoughts appreciated.