Disclaimer: Not a pilot or an aviation guy, just someone who's flown on planes before.
So, yeah. Assume A and B are the PIC and copilot, respectively, of a twin-jet plane (doesn't matter which one). B calls out "V1" and half a second later before V2/rotation speed both engines "magically" cut out. So, now what would A do? Or what would you do? Conventional wisdom says you should only reject the takeoff over V1 is the aircraft is incapable of flight, and I would point out that having both engines fail before you can even take off, with less than enough space to decelerate safely, is the epitome of an aircraft being incapable of flight.
Would this be a situation where there isn't really more to do but cross your fingers, and slam on the brakes, figuratively speaking, and hope that you stop before you overrun the runway or stop short enough that everyone survives? The thing is gonna stop at some point thanks to physics. Might as well ensure it stops as safely as it can, then assuming everyone's alive or not too badly unhurt, have a chat with the NTSB/local regulation authority about it.