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> **Possible Duplicate:**  
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> [Install Firefox 4 Beta alongside Firefox 3.6?](https://superuser.com/questions/160986/install-firefox-4-beta-alongside-firefox-3-6) 
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I am doing web development and I have Firefox 4 and I need to test in Firefox 3.6 with Firebug. Can I install both Firefox 4 and Firefox 3.6?