Failure of two engines on one side presents several big problems.
1. Performance - T/O data is based upon loss of only 1 engine (4 eng airplane). Unless very light weight, the airplane's speed and/or altitude will decay.
2. Controllability - If the loss of two engines is on the same wing, then the inflight minimum control speed is likely to be much higher than takeoff safety speed. Result? If working engines are kept at high thrust, the airplane will yaw, then roll due to the lack of rudder authority to counteract the severe assymetric thrust.
3. If it happens below decision speed, then abort. If above V1, an abort is almost inevitable also. Just hope that you can stop in the clearway. Better to have a controlled runway excursion than an uncontrolled crash.