Hello, and thank you for your contributions to OSM. 
In Denver, streets south of Ellsworth have the prefix, "South", included in the street name. Streets north of Ellsworth do not have the prefix, "North" included as part of the street name. You can use Mapillary images to view sample street signs, or if you live in Denver, you can easily see this on street signs in the city. Can you go back and fix the addressed you’ve added with the prefix “North”? 
Thank you :)