This can be caused by a long cable or docking stations.

Longer cables may be prone to ghosting, lines, double images, or poor focus. 

The improper shielding of the cables can cause a shadowing or ghosting effect also. 

We recommend to check the video cable and, if possible, use HDMI Premium certificate cable for long distance connection. And try direct connection without docking station and another device as cross check.

If you still experience issue, please contact ViewSonic service center.