Throughout the books, FFG has been inconsistent with the plural form of cannon (where both cannon and cannons can be acceptable). We get things like:
- Forward-mounted twin light laser cannon (with Linked 1)
- Forward-mounted twin light laser cannons (with Linked 1)
- Forward-mounted light laser cannons (with Linked 1)
All of these mean essentially the same thing, but they switch between cannon and cannons when referring to two or more weapons.
They also often do the same when referring to one weapon with multiple barrels, like the famous twin weapons (exception, I have not found a quad laser cannon referred to as quad laser cannons except when multiples of the whole weapon are involved).
I know, this is a little thing to most people, but it bugs me.