I'm wondering why nobody has built a tank with 2 main guns yet.
answering an 8 day old question here
Think about it this way;
The weight of two guns of smaller caliber would be more than one gun of higher caliber, which would slow the tank down for one thing. (Most of the time)
Secondly, Why mount two 76's when you can mount one 120, for example. The 120 would be generally more effective against tanks than the two 76's. It hasn't been done not because it'd be difficult, its because it'd be silly and impractical with today's modern tanks.
Plus you'd need an extra loader and gunner, which means more people risking their lives.
I'm talking about real life btw :P