IE I have a large group of contacts that were supposed to receive a drip but some may not if I did a bulk action to start campaign to same search group of profiles it won’t duplicate or start over to them only put those not already in campaign
Hey Frank,
This isn’t necessarily the case. A contact can only be in 1 sequence at a time, meaning if I have moved onto another sequence in the campaign, I could technically be added to the campaign again, depending on what the goal is, or the process of being added looks like.
If a group of contacts was added to a sequence, and was still working through that same sequence, and you ran an action to add a group that may contain some of those contacts, the contacts that are already working through this specific sequence would not be added twice, and that contact would still be at their current stage inside the sequence.
I hope this helps out a bit, with how the campaign may behave in your situation.
To add to what James has said, you will also want to avoid a common mistake (oversight?) where people set contacts into a sequence but they never get pulled out by a goal and they just sit there … endlessly. This would also be a cause for not being able to re-enter a sequence. Otherwise, a contact can go through the same sequence many times…just not many times at the same time 
@John_Borelli, this used to be the case and I always added a goal to pull contacts out of sequences if nothing else followed. But at some point that changed. Now, if a contact is in queue (everything in the sequence has been delivered/applied, etc) they can be added to the sequence again. Not sure when it changed.
I’ve still experienced just the opposite. Although, my OCD still doesn’t like seeing that number just ‘stuck’ there regardless lol