Double closing wholesale deals

[Devin Wilkinson]

I closed my first wholesale deal earlier this month using an assignment of contract but have not done a double close. A deal I am currently looking at may have a spread large enough to justify a double closing. I understand that a double close is just buying a property and selling it a couple hours/days later. My question is about the order of signing things. After I put a property under contract with the seller and bring the paper work to the title company can I Immediately sign a purchaser and sale agreement with the new cash buyer even though I do not own the property yet? Then do I just bring that to the title company also? 

I would appreciate if anybody could clarify this process a little more. I'm just not sure how I can put a property under contract to sell before actually owning it. 

Thanks in advance!