Hi everyone ..
Thank you for the answered providec..
Yes i am using 10.2 version .. so it means that it is normal in 10.2 if we get 2 authentication prompts if we use other alias name to access.
But for now, I have found another work around to this solution.
I used mod_rewrite module in apache configuration and now i am able to get single prompt even if I use any alias including localhost.