Duplicate class names in different libraries-Collection of common programming errors

Simple: Change the name of one of the classes. (No, this really isn’t simple as you have to change every usage of that class name in the library). Since objective-c is a dynamic language, there cannot be two classes with the same name. Classes are used at runtime to determine everything about the objects you create. To avoid naming conflicts, you should always use prefixes when creating shared libraries.

See Code Naming Basics, specifically the “Class and Protocol Names” section.