<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Disputes automatically close if they are not escalated within 20 calendar days. A dispute that automatically closes cannot be re-opened. </div></div>
This is a quote off of Paypal. So a dispute that hasn't been escalated within 20 days automatically closes, and can not be reopened.
I'm not sure if the same thing can be said for just opening and closing a dispute twice. I'm almost sure it's just a one time thing. You can't open and close disputes multiple times because it leaves too many areas for shady business.
You need to get it right the first time. Also this is a way to make sure that(selling virtual items) the buyer will not dispute the money and receive it back, along with your goods.