Based on the comparison above, I would have thought they were a rebadge as well, however you can tell from the photo they are not identical in construction, even though they are very similar in shape.
The Dewault has a metal gearcase that is screwed to the plastic tool body from the front, looks like the IR does not have a separate gearcase, so the front bearing and gears are supported by the plastic case halves - On the surface that might appear to make the Dewault more durable, but I've learned that clever design can often trump brute force - it could be that IR figured out how to make it lighter and just as strong - or it could be that it's just made cheaper and is not as durable.
What I find is curious is that the Dewault in this comparison is an 18V tool (they call it 20V max, but it's still 18 volts) and the similar looking IR are only 12v tools - that are sized like other companies' 18v's. It doesn't really make sense, given that Milwaukee, Makita, Bosch and others are going full -bore into the compact 12V (really 10.8 volt) products, and the latest versions are quite powerful and more compact than these IR tools.
I suspect IR is seeing cordless tools make a pretty good dent in their air tool sales.