So you feed the D/C with a 3-wire on a 2-pole breaker? Or your just using a 2-pole D/C fed by 2 wires?
Technically you have an identified conductor, since you have 120v. Nothing I saw in the CEC about them either though.
I think you fall in to the exception of that rule, I just don't see any reason to do it. If you put both on, you risk that someone thinks its 240/208. The next guy should know what he is doing, but Ive seen electricians make that mistake, let alone home owners /wanna be electricians. You could just as easily splice the identified conductor and leave 1 pole of the D/C open.