Region Difference on Multiple Curves

I'm trying to perform region difference on a bunch of curves for the purpose of generating notches.

I have rectangles to define the notches but when I 'region difference' them with the curves I want to notch it generates 700 curves instead of the 8 notched curves I want, which seem to be a 'differenced' curve for each notch then a ton of copies of the original un-notched curve.

I'm guessing that I need to do some sort of organising of the curves before I difference them?

Could someone enlighten me as to how its done?