Question:
Can I make more than 1 monitor connected to a recorder display different cameras?
Answer:
Yes you can; however, the recorder needs to support independent outputs - it will not work if the outputs are synced. This information can be found in the data sheet of the recorder.
Ex: The iDS-7208HTHI-M2/S has an independent HDMI and VGA output, so if you were to connect a monitor to both of them, you can assign them to display different cameras.
* screenshot taken from the iDS-7208HTHI-M2/S' data sheet.