You cannot cancel a sold item for that reason , a non payment before 4 days are up, and the ones left to you will either give you a damaging defect on your account, or the buyer can challenge the reason and eBay can place a defect on your account.
How do you know it's the same bidder? A new eBay account is opened many times a day, could just be a new member.
You'll need to wait the 4 days before you can cancel for buyer has not paid eBay send a reminder too, to the buyer to pay, after 48 hours.
@dancin2nite-2008