Group quest bug

Okay my friends and I have noticed that if there are multiple groups in an area, as we cannot all be in the same group being that there are too many of us and whatnot but want to be near each other for protection, that if we are both doing the same group quests, it'll affect the other group's contribution. This means they aren't getting the proper growth and marks for what they actually did, vs what the game thinks they did.

To try and explain it better:

Bob and Gary are in group 1 and Suzie and Carrie are in group 2.

Group 1 and 2 have quests to pick up acorns. Bob and Carrie hang back to allow their friends to get the acorns for the quests, Gary grabs 50 acorns and should have 100% contribution but because Suzie is also grabbing acorns, his contribution drops even though Bob never picked up an acorn.

And even if this is to prevent a mega group, what if it is just two separate groups that just don't want to fight, that's not fair to them either.