In which case, assuming he has ~5 points RC on each gun... (not all that hard)... he's doing nothing wrong.

And he's nowhere near engaging 8 targets a pass.

Secondary target penalties still accrue though... regardless of him using 2 different weapons.
Don't forget the off-hand penalty if he's not ambidextrous.

Remember targets need to be adjacent (w/in 1m of each other) to split a long burst into 2 short ones...
In which case he STILL needs to split his dice pool between the targets.

Ah, that wasn't clear. I thought you were talking about my complete overboard double double long burst scenario. So, he's just using the two guns to double up his ammo and RC in exchange for losing half his STR RC and any laser/smartlink bonuses?

Seems like there's not much to be done about how your player is running things. I wouldn't bother a human using dual smgs that way, so a Troll using dual ARs sounds fine to me.

Since there is no "special case" rule for firing two weapons, one with the first Simple action and then the other with a second Simple action, I would take the blanket rule that all recoil stacks to mean just that. After all, recoil is something that is affecting the shooter, not the weapon itself per se.

For game balance, I absolutely agree with the rules on shotguns and heavy weapons having double uncompensated recoil. Those things make a hash of my NPCs!

The wording is unambiguous. Recoil accumulates per weapon unless you fire two with the same simple action. But even if uncompensated recoil would go over to the other weapon, getting 5 RC on a automatic Pistol or SMG is not so hard (GV3, Personalized Grip, Underbarrel weight).

See above

The character started out as an ork using 2 SMG's.

You only lose smartlink bonuses if you fire two weapons simultaneously.

You can also do crazy things like 2 short wide bursts at once, followed by a narrow burst with each.

The troll in question won't always be using his assault rifles - I impressed on him the deadliness of HTR teams. His "quiet" weapons are silenced, electronic-fired Praetors with easy breakdown named Silent and Deadly. -9 dice on Perception tests to notice them with subsonic ammo (which in my game doesn't reduce range, but can't be used in anything larger than an SMG) - if you aren't in the same room, odds are you don't hear him. Maybe I should suggest he get traceless walk so he can sneak up on people

Never suggest something to a player unless you have a counter.

I have a comment on the issue of dual wielding and firing one weapon at a time (per action).

Now the rules are pretty clear that the drawbacks of firing two weapons at the SAME TIME don't apply here. So the only thing that does apply is the off-hand penalty (negatable), and the fact that you don't get RC from stocks (retractable or otherwise).

Thus you can fire two Ruger Super Warhawks per phase without any recoil or dice pool reduction (with ambidexterity).

The issue is with automatic weapons though. Although you can fire both, the rules actually state that you can only fire one long burst per phase. It doesen't specifically say that having a second gun allows you another long burst (even though it's a fair assumption). Short burst however can be fired more than once, even twice on full auto, so no problems there. So you could probably fire one short and one long burst with two SMGs and be able to compensate recoil even better than if a single gun fired all those bullets. It even makes sense somehow - after all the short break in firing means each gun has some time to finish recoiling before it's fired again (next initative pass). Also, since getting 2 RC is extremely easy, firing two short bursts with two guns makes recoil insignificant. Sure, you can do the same with a pimped up ares alpha, but never as cheap as with two SMSs with say Gas vent 2.

Sorry to jump in on this so late, but for years I have used a houserule for recoil that states that it is cumulative over an entire round instead of an initiative pass. Now, before anyone screams about how unfair this is to those people that spend good essence/power points to get those extra IP, let me finish. A character can use a "Take Aim" action (a simple action) to reduce all built up recoil modifiers instead of gaining the usual +1.

This is a rule I've been using since early third edition days, and no matter the group I run for (since I can never find someone to GM for me) it's always been accepted fairly easily. I have always thought it was silly that the runner firing 3-4 times as fast doesn't have 3-4 times the recoil because the weapon will in fact be moving and jumping more in their hands; no matter how cool their nervous system is.

Regarding your other question about dual wielding but using different actions, here is how I've GMed it.

Recoil from 1 weapon does affect the other. Simply put, if you move one side of your body, it affects the other. I also say that the "Change Linked Device Mode" action (a free action) to swap which weapon is connected to a smartlink. Smartlink bonuses do not apply when firing both weapons as one action, but I've no problem with using a free action to use them in this capacity. I had to address these rules when a player wanted run an old gunslinger inspiried character to dual-wield Ruger Super Warhawks.

I find it fairly ironic that this entire thread has been a defense of trolls dual wielding HVARs without cumulative recoil and now there is concern about how to keep such a character in check. I think that train already left...