How to display two pdf files side by side simultaneously on the same screen?

I assume that you're using Adobe Acrobat Reader DC to view pdf files.

• Open Acrobat Reader (with or without a file) and click Edit > Preferences (or press CTRL+K).
• Select "General" in the list of Categories if it isn't already selected.
• UNcheck "Open documents as new tabs in the same window (requires restart)"
• Click OK
• Close Acrobat Reader

Open your two documents, click on the Title Bar in one window and drag to the left side of your screen then click on the Title Bar in the other window and drag to the right side of your screen.

Thank you LemP for you reply.

It was very helpful.

In the meantime I have come up with another solution see below.   

METHOD 2 ADOBE ACROBAT READER AND BROWSER

• Right click on the first PDF file and select “Open with Adobe Acrobat Reader DC” and then minimise it.

• Right click on the second PDF file and select “Open with Firefox” (or another browser) and then minimise it.

  Both files can then be displayed on the screen simultaneously using Adobe Acrobat Reader DC and Firefox.

I hope other might find this helpful as an alternative.