I've seen them in radiators before and always assumed that they are there to serve as expansion joints and protect the coils from separating with temperature changes.I emailed the seller - Big Dog Aftermarket - and they just responded to my question about the cuts:
"Charlie207,
I am going to forward your photos to Champion as we do not know if the
cuts are supposed to be there or not. We have never seen that before...
I will let you know what they say."
If you guys are seeing them, and to my uncalibrated eyes they look evenly offset top to bottom, then I am assuming they are meant to be there.