As @patryk_turowicz indicated, it seems that the PSC ID - like the officer ID - serves only to identify that particular PSC entry for that particular company:
So in the PSC snapshot data set, the part:
... I'd expect the link /company/09145694/persons-with-significant-control/individual/bIhuKnMFctSnjrDjUG8n3NgOrlU to be unique and the ID bIhuKnMFctSnjrDjUG8n3NgOrlU wouldn't refer to the same entity even if you did find it occuring in another company.
It should probably make this explicit in the documentation e.g. PSC list resource.