Sure 747's (-200, 300, 400) can fly on 2 engines. In fact, if neccessary they could also fly on 1 engine too. After all, there are marvelous stories where 747 were able to decend, and land safely from 10,000+ft when all engines were shut down.

But I would doubt it took off with 2 engines only, I think that's not true. For 747, it's not uncommon to keep on flying with 3 engine if 1 dies out (especially if you fly over ocean). But they wouldn't take off unless the aircraft is in perfect condition. However, I think it is technically possible to take off with 2 engines, they are designed that way.

PS. 777-300, despite its weight, can also take off and fly with 1 engine only.