Please help to identify the camera

Recently I bought about 450 diapositives shot with 6x6 medium format camera. Can you please tell me which camera was used? It leaves two notches on the left side of each frame (see below).

Shot with a Hasselblad !

John S

Thank you John! I was hoping to hear something like Rolleiflex 6000, but I have to be less ignorant and pay more attention to my own Hasselblad, which I have since 5 years. Maybe it is time to shoot portraits with bright background