No. The assignee must be a single person, otherwise you run into the unmitigated disaster that in real life, someone will say "I thought someone else was responsible. Don't ever allow that to happen
There is however, no harm in indicating secondary people who are involved, can take over if the assignee needs to change, have an interest, etc. You can use other fields for this - some people use the built-in watchers, the rest tend to add custom fields - a single or multiple user picker, or a group-picker if you want to name an associated team.
@Nic Broughwasn't there an effort to use a custom user field to have a co-developer setup where two people were working on the same project at the same time? I think it may have fallen out of favor perhaps for the same reason.
I agree with Nic though on the potential pitfall. Why not use a subtask to add people to the issue that they are both working on? I've done that where I have three technicians building different parts of the same main assembly. One of them is responsible for the main final assembly and the subtasks (or linked tasks) are farmed out to others and block the main task from completing. It gives the main task owner some incentive to ask for help on his roadblocks or to negotiate a solution with the roadblock.
Applying Trello magic to Jira projects Introduction Lately, I have been writing a lot about Release Management (e.g. a few of my previous articles- One, Two and Three). ...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events