Airtasker does not currently support the ability to assign more than one Tasker per task.
Need more than one Tasker? You can easily repost tasks by clicking Post a similar task (using the desktop site) or Copy task (using your app). If you’re posting multiple tasks, make sure to include as much detail as you can to describe your requirements to Taskers. They will need to understand that you will be selecting a number of Taskers to work on it. If you’re unsure how to describe it, check out some tips here.