When the game says 2 x medium cannon 7.5 damage. Does it mean 2 x 7.5?

For example the Marza Dreadnought;

Does 2 x medium cannon 2 x 7.5 (15 damage)or a total of 7.5 Damage meaning each cannon does 3.75.

Obviously 50 armor penetration is per cannon NOT cumulative to 100 penetration.