How to open the same document in evince multiple times?
In evince you can use File --> Open a Copy to open another window showing the same file.
In Ubuntu 18.04 I found no "View in new window" but did find "Open a copy" under the "File Options" button on the far right. This opens a new instance. Later I found that you won't see the content until you scroll it.
The accepted answer for this doesn't work for Evince anymore. To view the document multiple times in that program, select "View in new window" from the menu.