So called marriage usually comes from antique dealers, rather dubious ones. If your aunt bought it new you don't have to doubt, but I guess anything is possible when we buy second hand. I have come to hate alterations, it seems like a good idea at the time and it can work for a while, but I have had a set of chairs gone bad because my mother decided they would look "ligher and more elegant" if she sawed of the cross section securing the legs. They don't look bad now, but they needed further work later on to secure some joints and there's only two left (more pressure on joints and they broke). Another time my great aunt decided to saw off a section of the legs on a victorian or edwardian table. The lower parts of the legs are solid but swirly bits, they were taken off shortened and put back on. The table worked fine for it's intended alteration, but now it's just a bit short for the chairs that go with it. Have you ever tried to remove paint from nice wood or veneer? Arghhhh....
You should be able to notice slight differences in wood and wrokmanship in "marriage pieces", but it needs a keen eye and closer investigation.