Basically, Kansas copied the Missouri Kansas City:
During this time, other settlements were developing across the river on the Kansas side in Wyandotte County. Some of these small towns incorporated as Kansas City, Kansas, in 1872. By naming this town after the growing city on the Missouri side of the state line, city leaders in Kansas were able to capitalize on the success of Kansas City, Missouri. It’s also possible that the people in Wyandotte County felt that they had more right to the name “Kansas City” than the people of Missouri had.