No. It is not possible.
When you have a task played and you press play in another one, a message will warn you: "Another task is running. (and will give you the name of that task). Would you like to pause it and play (name of the task2)?". Then you can decide wether to accept it (green tick) or cancel it (red cross).
We did that following the logic that every moment we work and bill a certain project we cannot be working and billing another one. This way you are certain that you are focussing and tracking specifically every project. BUT, super-power functionalities could be given to special users if you really ask for them ;)