Choreography of making many yorkshire puddings
I would buy two tins, for the reason that one of the most important factors for successful Yorkshires is a good hot oven. This is required to convert the water in the batter into steam quickly, causing the puddings to rise. Your oven loses a lot of heat when you open the door, so you will more than likely get a poor rise on your second batch if you reuse the tin.

So, I would use two tins, then you can keep that door closed until the last possible minute.