It's definitely not just a single pass + travel pass. My calipers measure the support walls to be 0.8 to 0.9mm.
I've imported a test model into Cura 15.04.6. Here's the result (and you can see the original model from Fusion 360 in the background):
The widths in the original model are 0.21mm, 0.41mm, 0.61mm, 0.81mm, 1.01mm.
Here's the result from printing the model. It's a little hard to tell from the picture, but you can see it printed 2 lines side by side, even on the thinnest part:
The thinnest part of the model that printed is between 0.8 and 0.9mm:
This is the profile I'm using: TestPrintSettings.ini