Hello Manesh,
I can see in which direction you want to address your question(s), but I cannot understand what is exactly the question or the problem. Missing some verbs, the issue/log, a description of your current setup, etc.
For now, but I am going to give long shots since I cannot understand you yet:
Indeed, Auth domains with the same name are not a good idea. You cannot re-use the username on different account tabs either. All must be unique, else it won't work.
Please let us know if this helps or if you need more. If you do, please help us by rephrasing your question(s)! 🙂
Best regards,
Juan