Hey Colossus#TR
You can find the full information on the healing tent here.
A quick answer to your question is this:
Regardless of the number of healing tents, there is only one queue. Building additional healing tents will not create multiple queues, it only creates more capacity.
Your healing time will be influenced by the highest level healing tent in your village. For example, if you have 5 healing tents. 1 is level 20, and 4 are level 10, all troops will be healed at level 20 speed (which is the same speed as a level 20 Barracks or Stable for the same troop type).
Best,
W.D.