UnityEngine.Networking.dll added twice

when i build window app, always tell me

"File Temp/StagingArea/Data/Managed/UnityEngine.Networking.dll added twice
UnityEditor.HostView:OnGUI()
"

"File Temp/StagingArea/Data/Managed/UnityEngine.UI.dll added twice
UnityEditor.HostView:OnGUI()
"

and i have no idea about how to deal it .

PLZ help me.

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