Normally I like your art because it has a realistic feel to it. But this isn't one of those times. Dual main guns on a tank is just ridiculous. Could you perhaps take one railgun away? Also, I notice you always seem to put a large 25mm? gun on the tank, this too is a bit much. You could carry far more ammo with a heavy machine gun and/or two general purpose machine guns.
It would be cheaper and less complex to have just one main gun. It would also take up less space internally, the loading mechanism which is already bulky itself would be less complex. You could also carry far more ammunition for one main gun then you could for two because more space would be freed up inside the tank.
Yeah cause you know, the military never thought of that right? Do you have any idea how fast a human can actually load a shell? A well trained loader can load a shell faster then most auto-loaders. And with a railgun, there is no need for a heavy brass casing or propellent, so a human could load even faster. There is absolutely no fucking need whatsoever for dual main guns. PERIOD!
As for auto-loaders, they are bulky and complex. Now imagine how much more bulky and complex they would be in order to feed dual main guns.
Dual main guns on a tank like plasma weapons and star fighters may be cool, but cool isn't always practical. I promise you that you'll never see a main battle tank with dual main guns now or in the future.
Well, there are plenty of double barreled tanks. Tungaska, Skink... almost all SPAAG's in general. Perhaps this is the 2142 equivalent to those. Capable of killing tanks and aircraft. Sure, you would deplete your ammo quickly, but you'd bring a lot of kill to the game.
You also make it more cramped in the tank. You will find that such vehicles are the exception and they use much smaller calibers then a MBT. There are several very good reason why no nation makes dual main gun MBTs.