PS v 21.2 and PS v 20.0.9 How to keep both versions in my applications on this iMac

Recently finished updating Photoshop (and CC, and all apps in use).  Kept PS v 20.0.9 in my applications on this computer, and installed the new PS v 21.2 .   They were nicely sitting side-by-side on my bar.   Double-checked updates on my Creative Cloud to verify that they were both installed ✓ and both up-to-date ✓.  PS v 20.0.9 is gone, this morning.

How might I keep v 20.0.9 actually on my computer?  What have I missed?

Now shows as Up-to-date in the CC Panel but is removed from my OS.  (Unless hidden?)  Prefer/need to continue using the 20.0.9 version, for now, and would like to keep it actively available when working off-line.  

I suspect there is a permission, in this OS, or in the Preferences for Photoshop, that I did not check/select properly.   

Reviewed/read every panel, and checked according to my work-flow preferences.✓  Checked my OS System Preferences ✓  ... or so I would like to think ... .

Looked for posts regarding this - thought I saw some the other day when looking for other info - but cannot find anything, today.  Is this the right forum to ask this question?

Thank-you, in advance, for clarification!  Your community is awesome - knowledgable and so helpful!

macOS Catalina v 10.15.5 (plenty of memory/storage)