If you only connect some of cameras(not all cameras) to your?NVR/DVR, and see the same image showing on two or more channels like below, please disable those unused channels to have a try.
Here is the method for how to disable the unused channels:
1 Right click your mouse on the monitor screen, go to Main Menu, click System.
2 On the system page, please go to Digital.
3 On the Digital Channel page, choose the unused channel number and uncheck the Enable box.