This situation came up last night with one of the Ord Mantell quests about a few troopers having a gambling run on the unexploded bombs, whether you want to attempt it, bid on it or if roleplay inclined, want to report them to your superiors.
As a group, my partner and I did that conversation and my smuggler won the roll wanting to infact run in it, while she wanted to report them. After the conversation, we then both had the quest to talk to the person to either run or bid.
For these quests where the conversation wasn't final (ie usually the end of a quest line where someone dies from a dark side choice), the choices we make in the conversation should impart the respective step by your choice and not the whole group.
The example for above is with Republic Roulette: Questionable Ethics.
Player A thinks "Goddamn! This is a hoot! I'm going to run it!"
Player B thinks "Meh, but I'll throw a few creds in."
Player C thinks "But, this.. no.. sorry I cannot. I'm going to talk to my superiors about this."
Roll wins on A or B, yet player C gets the same quest as whole group and nothing about heading off to superiors.
In truth, an easy fix would be give the choice a trigger that allocates the quest if applicable.
The other option would be make it so those quests are OR quests. Bid, Run OR Report.