Adding multiple members of the same class to a group does not impact the drops given. The game only registers whether a class is present in a group, not how many of them are present, when determining drops.
Our guild has an overabundance of Consulars. We generally have 4-5 every night we raid. Generally we do two clears of normal content and two of HM/NMM as well as Denova Story.
We've noticed a very big bias towards whichever classes are represented least in the Op group, to the degree where we can almost predict what each boss will drop. Our raid yesterday is a prime example. We were running a few lesser geared people through EV HM to get gear for those wanting to do Denova. Our group makeup was 2 troopers (vanguard tank, commando heals), 2 knights (2 guardian dps), 4 consulars (sage heals, shadow tank, 2 shadow dps). Specifically we were looking to gear up the shadow tank, but prior to starting, due to previous runs, we guessed that there would be a lot of knight and trooper drops. Sure enough, we geared up fully one of the guardian dps and the trooper tank. Only one consular piece dropped the entire run.
We've seen this happen almost every Ops run since the patch change. To put it even further into perspective, our Knights are fully geared, their offspecs (if applicable) are fully geared and their companions are in full Rakata. Other than the occasional drop, our consulars are struggling to get gear. We're even considering limiting the number of consulars in Ops in order to gear up the mains that require the gear most.
I think the change to the loot system for Denova Hard mode is a great change however, given the loot issues we have with the previous tier. We don't believe that the loot drops on normal and in the previous tier are not biased in some way towards the least represented.