Darn Google bots are crawling both URLS:
http://MYWEBSITE.com/index.php?topic=#
http://MYWEBSITE?topic=#;PHPSESSID=to4kviraflqr6gota2qi38df64
How do I stop this insanity?
A little update --> I added Disallow: *PHPSESSID* into my robot.txt.
It depends.
Do you want to accurately know how many Google bots are on your site at one time? If the answer is yes, then there's nothing you can do.
If the answer is no, and you don't care that your visitor count will be massively overinflated, there are things that can be done about it.