No connection between the 2 companies that I am aware of...one from Cincinnati and one from Galt (Cambridge).
John Steptoe: http://www.vintagemachinery.org/mfgindex/detail.aspx?id=2177
R. McDougall: http://www.vintagemachinery.org/mfgindex/detail.aspx?id=370&tab=0
Of course, there are lots examples of good research showing undocumented ties from the past when records for these sorts of things were not well preserved. An example of that is over on the woodworking side, where there has long been speculation and decent evidence presented of a connection between Walker-Turner out of the U.S. and Beaver Tools out of Guelph back in the WW2 era.
I am not aware of any other McDougall shaper in the flesh today besides the one I have, and I have been watching and looking for the past decade now. I know of several of their lathes near me...in fact a buddy of mine has one. Hence my suggestion in the ad that it is "historically significant". Notice there are no examples posted up on the Vintage Machinery site. I will let the new owner decide as how to document it there with pictures, etc. and discuss that with them. And if they don't want to do that, then I will see to that.
Although I see considerable materials showing John Steptoe to be very active in the early days of the metal shaper space it is noteworthy to me that there are few examples of actual machines showing on the Vintage Machinery database. I am personally a big advocate for posting up machines there for the betterment of posterity and mutual learning and knowledge transfer, especially on the companies and models that are not otherwise well represented. These resources are invaluable to folks like me researching these machines and their associated accessories and tooling as we refurb/restore them. Please consider posting up your shaper and paying it all forward...