The Alessandro Mattei listed in the final branch of the family tree above, though sources suggests he undertook an ecclesiastic career, is not Alessandro Mattei (1744–1820). Ironically though, the latter Alessandro was also nephew to a Luigi Mattei; born in 1702 who later became a cardinal (not the military Luigi Mattei listed above).
The Alessandro Mattei from the final branch of the family tree is not the same as the one mentioned in sources who pursued an ecclesiastical career. This Alessandro was also a nephew to a Luigi Mattei, born in 1702 and later becoming a cardinal (not the military Luigi Mattei listed).