Uniqueness of VuMarks

Hey,

I have a general questions about VuMarks. Imagine you have 2 VuMark databases imported and enabled in the same (Unity) project. Both are the from the very same same template uploaded to Vuforia, except the image in the center. Is there a case, where a Vumark can be generated, which result in the very same code? So the tracker could get in trouble detecting the Vumark, because the border an code could match both VuMarks? Or does the little overhead ensure, that the generated "code" in the vumark is unique for each VuMark template. Even if two are some sort of the same?

Thanks!