My guess is you'll be ok. I'm sure your laptop is protected to voltage surges and as photon said, you are within tolarance.
This is the non-application side of me, but if you split the cables, you could make a voltage divider out of the adaptor. Knowing your load and input power, you could make a little circuit to give you your desired input voltage to your laptop.
Don't blame me if something goes wrong though
Oh, and check your laptop to see if it gets warm. If it does get warm, then you might want to unplug it.