Yes as long as…
  • you install a copy of the browser in the /Users/username/Applications folder on separate user accounts and
  • Remove all internet plug-ins from /Library/Internet Plug-Ins and install a custom set in /Users/username/Library/ Internet Plug-ins in each account
  • Then login to the different accounts to use the different copies of the browser.
If your browser is Safari or one of the third party bowsers, email clients, etc. that use Apple's webkit they may still be using the webkit that is embedded in OS X. You could get around that by using multiple drives each with a unique installation (not a clone) and booting from the "private" drive(s) when wish a high degree of hiding your browsing.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein