Cookie issue

[eluser]pallavi312[/eluser]
Hello,
I have 2 urls.
http://sample.com/old & 2 page-http://sample.com/old/user_reg/sleep_test
& http://sample.com/new & 2 page-http://sample.com/new/user_reg/sleep_test

on both these code is same regarding session & cookie variable setting

but when i access http://sample.com/old & in same browser if i opened http://sample.com/new
it redirected to http://sample.com/new/user_reg/sleep_test

please let me know how to solve issue even if i have entered diff cookie name on both sites.