Status 3 error: Err_Double_Spend??

[cjcoopertag]

So I am getting the above mentioned warning error in my log? Does anyone know what that is or better yet how to overcome this? I have almost 600 plots and no xch and opened up the debug log today to see a mount of this errors. Also, I have not had a single harvester transaction achieve the 5 seconds or less...the lowest has been 5.1 seconds but that is few in far between all of the mentioned errors in the log.

I have two PC's dedicated to plotting and two that are harvesting.

I appreciate the input