Alright so, to summarize mine and Flint's findings regarding the medpacks:
Occurance:
If one player spawns with 6 medpacks, and then drops it to another player who has not spawned with, nor picked up medpacks at any point in the round, the amount of medpacks increases by 6. These two players can not repeat this without one of them dying (that player can again, not spawn with or pick up any other medpacks before the 12 medpacks are passed on)
Example:
Player 1 spawns with medpacks
Player 2 spawns without medpacks, not having had medpacks in his inventory before this
Player 1 drops medpacks to player 2
Player 2 picks up said medpacks, the amount increasing by 6.
Player 2 now has 12 medpacks
Player 2 now drops said 12 medpacks, which player 1 picks up
Player 2 dies, either by enemy or himself
Player 1 drops the afforementioned 12 medpacks to player 2
Player 2 picks up said medpacks, the amount increasing by 6 again.
Player two now has 18 medpacks
Repeat
So one needs either a large amount of people spawning without medpacks in a battle round, or a constant stream of cooperative companions in a deathmatch round, all of which also spawning with no medpacks.
Basically if you were to use it in a battle round, you could only have as many medpacks as the total player amount on your team could have taken had they all spawned with their individual sets. This assuming the entire team are troopers. Had there been force users, they would also be able to do this with troopers.
In battle there is no significant advantage in doing this, other than collecting a large amount of medpacks in one spot, with only one medic, which then leaves open the opportunity to constantly shoot others, instead of multiple people having to heal their team. The downside here is that if the one medic with all the medpacks dies, without having had those medpacks in his hands, that team has now lost all healing capabilities.
Quite a weird bug, a tad unprofitable, but still applicable in events. I believe it works with other items such as grenades and detpacks, although i have not personally tested this.
Causes
I assume it has something to do with M&Bs ammunition system. Each player has a total amount of medpacks possible, purchasing medpacks in equipment store will unlock these, but picking up another set would then double the amount you could have. Having the medpacks of another player then 'unlocks' the amount you could have had.
Fixing this is for the accomplishment of better men than i.