So currently when you upgrade a T1 gun mod to a T2 you have to put in 5 T1 mods and they each have an equal chance (20%) of being crafted. If you were to put in two of the same mods and 3 different ones while trying to upgrade the chances of the mods being crafted increase across the board to 25%. I think that instead of increasing the odds of all the mods it should only increase the odds of the duplicate mod.