Have accepted them only because a named pair looks better than a nameless pair. No sources have been provided, and no reliable information seems to exist.
Col. Nathaniel Pope did marry a "Lucy", but her birth name has not been discovered.
A later Nathaniel Pope *did* marry a Lucy Fox, but that was in the 1700s.
I suspect someone has been working with one of those late 19th-early 20th century cod genealogies which cobbled up information (and often invented much of it) for American families eager to find illustrious ancestors.