there is no facility to record PIP unless the claimant can provide dual recording facilities for themself.
It seems so bizarre to change normal procedures like this I'm wondering whether whoever passed on this information to Slugsta got it wrong. Expecting people to bring their own recording equipment with them would illegally discriminate between claimants, for example (the few who had such equipment being comparatively advantaged over those who didn't).
I can quite believe PIP assessors haven't bought in any / enough recording equipment but I struggle to believe they're not required to have it available and use it when the client requests. Would suggest checking with DWP, your MP, CAB or anyone else likely to know.