Item listed twice and need to remove one...

You'll have to end one listing early on ebay's help page. My wife just went through the same trouble. Took her all night to upload images then the system got stuck when she tried posting. Her item posted twice, just like yours.
Don't bother asking Auctiva's personell for help or for a refund. They won't dare admit they have any problems. No matter how many people have the same old gripe, day after day after night after night...

Write down the item # and call or email Ebay with all the information. They will give you a credit if you explain to them that the third party listed posted it twice. You'll have to use the end my item early feature through Ebay.