Lead List Scrubbing

[Cameron Chesney]

BP Team, I have a few lists purchased over the last few months that I have been sending direct mail pieces to. I have purchased from the same company each time with the same parameters each time. What is the simplest way to cross reference my lists to make sure I am not sending an initial piece twice to someone? I suppose my concern is I might get a list in back to back months that contain the same absentee owner in both lists. Has this ever happened to those of you purchasing lists? Or is it even possible? Thanks for the feedback - Cameron