Another - "Dont know this is the correct thread" post

Some background: I applied 2 position in this company 9 months ago and I successfully got one of it and got confirmed last month,

but last week my HR called one of my referee (he is my fren) to ask about my performance and some reference check.

But I had just finished my probation in this company. Is this usual for HR to cross reference? Or they are looking at my other application without knowing I am already in the company.