Change in account 1 gets pushed to account 2

Hello,

In SAP HR we have 2 PERNR's where if I change the name of employee 1 through infotype 2, this change also gets pushed to employee 2. I don't know how it's possible.

So if I change the name of person 1 to "Stef Renneboog", automatically the name of person 2 changes as well to "Stef Renneboog".

How can we delete this link between these profiles?

Thanks,

Stef