Error: Make sure that the class defined in this code file ma

The website is working fine now I added MenuLeft.ascx into the folder "C:\WebSite2010\WebMaster\Controls\" when pressing the Rebuild website button with the error "Error: C:\WebSite2010\WebMaster\Controls\MenuTop.ascx.cs(14): error ASPNET: Make sure that the class defined in this code file matches the 'inherits' attribute, and that it extends the correct base class (e.g. Page or UserControl)". Note that the folder "C:\WebSite2010\Controls\" already has a file with the same file name: MenuLeft.ascx now I copy the declaration of 2 files with the same name, how do I change the code ?

in the file: C:\WebSite2010\Controls\MenuLeft.ascx