What I meant is that "flat" jacketed wire is not always flat enough. It is much thicker and less flexible than bonded ribbon type wire.
Here is an example of marine ribbon two-conductor -
Ancor 16/2 Flat Ribbon Cable Red/Black - 153110 - BoatersWorld.com
Originally Posted by sailingdog
My post was directed towards Brak, who mentioned that it was difficult to find flat duplex wire.