Now, if you posted extra items and immediately stopped them:
You can use any one of those auctions to 'relist' an item. You don't have to list the same item. You can change everything and anything about the listing. You will be charged all the applicable fees.
HOWEVER, and this is where the savings come in, IF the item sells this time around, you will be credited back every penny you paid for the second listing. You will only be out the initial 10-cents.
The risk: If it doesn't sell, you're out the initial 10-cents + whatever other fees you paid the second time.
I am not making a statement on whether or not it is ethical or legal or within eBay's TOS, I'm just trying to clear up the confusion.