Issue adding category from code with same segment name

In my project there are two sites and each uses its own catalog. Category with same name can be in both catalog. When I am trying to add Category with IContentRepository it is giving me exception that Category with same Url name already exists. I found that there is flag named 
 episerver:commerce.UseLessStrictEntryUriSegmentValidation" that I can turn on in App.Settings, but I am getting same exception. Am I doing something wrong? 

Thanks, 

Sudip