Is this a single system or duel master cylinder ?

hi there,
I am having my brake servo rebuilt and lined with S/S bores at great expense , and thought that while I'm at it , that removing the master and installing a new seal kit would be a good idea.
I want to order the parts from Wins , but not sure if it is a duel system of single?
The rear pipe goes to the brake servo at the front of the car.
See picture:


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