6.x-1.01 and 6.x-1.1 are recognized as the same release?

I tried to make a new release 6.x-1.1 by tagging 6.x-1.1 to a current 6.x-1.x (6.x-1.x-dev). However, when I tried to do "Add new release" and "Create Project release" (see a screen shot), the release page says: "The version you have selected (6.x-1.1) is already in use by another release." Then I clicked "another release" link, it goes to 6.x-1.01 release page. I am not sure what is happening here.

Are the release of 6.x-1.1 and 6.x-1.01 recognized as the same release? Should I need to tag 6.x-1.2 if we have 6.x-1.01 release? Or, is there some way around to break a relationship in between 6.x-1.01 and 6.x-1.x? Please advise me about it.