I believe it's (bulletin bonus)*(number of bulletins)
In don't think so. In some games (like LoL and DoTA) We have "additive stacking" and "multiplicative stacking" Here are to examples From League of Legends:
Additive stacking: if your champion has two items granting +100 health each, your champion has 200 bonus health.
Multiplicative stacking: If your champion has armor granting 10% damage reduction and an item granting 10% damage reduction, you multiply the damage factors—0.9 and 0.9—to get 0.81, which means your champion has 19% damage reduction (against physical damage).
So in CoH for lets say increased armor, if you have 100 armor and two "Add 4$ amor" it will be like this:
100+(4% of 100)= 104
104+(4% of 104)= 104+4.16= 108.16
Well first of all, this is not a HUGE difference (I feel like a stupid nerd explaining this, who the hell cares about 0.16% armor
) . And the reason that I say the games uses the latter kind is most of the time in programming, calculations are done from top to bottom, So the game checks for a bulletin, applies its effect, then checks for other bulletin and applies its effect again UNLESS the engine is told to add the effects,then to apply it.
I might be wrong though, just my thoughts.