Are you completing your daily quests? I am legacy level 30. I have two level 50s but focus more on my main than I do on leveling characters. I make time to do my daily quests on Ilum and Belsavis on both and they amount for most of my legacy experience gains. I get roughly half a legacy level a day just from the daily quests.

It is not limited to bounty hunter / trooper. It spawns 5-6 copies of my sniper each time. The boss has an immunity to damage buff which makes a constant 'burn' method difficult. I could handle it spawning 2 at a time or even just 3, but we get a constant stream of them.

Imperial side has similar issues except with Snipers.

I'm a sniper. He sometimes double spawns clones of the other group members (Jugg, Op, Sorc). However he constantly, now and before 1.1, spawns 5-8 of my character. It is every attempt and the only time we kill him is when I get cloned last due to him being immune to damage while the direct clone is up.