Yes, there was more than one Negro National Baseball League. The original Negro National League, founded by Andrew “Rube” Foster in 1920 succumbed to the financial pressures of the Great Depression and folded after the 1931 season. In 1932, the Negro Southern League was black baseball’s only operating major league.
The second Negro National League was organized in 1933 by Gus Greenlee, owner of the Crawford Grill in Pittsburgh and, reputedly, a leading “numbers” operator in that city. Greenlee’s new league began the 1933 season with six teams that included Cole’s American Giants (formerly Foster’s Chicago American Giants), Baltimore Black Sox, Nashville Elite Giants, Detroit Stars, Columbus Blue Birds, and Greelee’s own Pittsburgh Crawfords club.
The reformed Negro National League continued in operation through the remainder of the 1930s and throughout the 1940s, ultimately dissolving at the conclusion of the 1949 season.