robot.txt and disallow google bot

I have added an seo tool to my forums , and it asked me to added the following robot.txt ,does this robot ok . does it have any problems with bots . am just want to make sure .
it was just upgrading to the currently used one . in goal to avoid duplicate content on my site was the need to add robot.txt .i want to ask too . does duplicate content in the same website domain cause problems with google .