ListSource: how do I make sure I don't purchase the same list

[Alex Finken]

Happy Easter everyone! I purchased my first absentee owner list from listsource a couple days ago. With my criteria it came up with 6000 properties. I decided to just buy 300... I saved the list for future use. Well, today, i figured i'd go ahead and purchase another 500 from that list of 6000. Is there any way, to make sure I don't get the same properties I already purchased. I don't want to spend $100 and have 100 of the properties be ones I have already purchased... I did the "purchase partial list", and the "only ______ leads" option. Thanks!