Category properties let us set a
Use for identification setting. What is this used for?
Use for identification:
Select the option if you want to uniquely identify Component Presentations on the published Web site.
If you develop a Keyword-based navigation, selecting Use for identification ensures that no two Components tagged with the same Keyword have the same name. Component Presentations based on these Components will be uniquely identifiable using a combination of the Component Title and Keyword on the Presentation Server.
Note: You can identify Components on the published Web site by their Content Manager URIs, or you can tag them with custom metadata and query them, or you can tag them with Keywords to organize them into a hierarchy for navigation.
*Source taken from SDL LIVE Content