Sounds like one shed with two large "columns" to me. If the total square footage under the roof complied with they by-law I would probably build it. A solid wall as the rear wall of the gazebo enforces that it is a single structure. You would need to pull a permit though as it would exceed 108 sq ft. Permit helps you when someone inevitable complains.Just looked at Brampton's accessory building bylaws, max 2 allowed. I love the idea of two sheds with a gazebo between. I wonder if a pop-up canopy between is ok since its not permanent.
Sheds and Accessory Structures
www.brampton.ca