Using older versions of Outlook for Mac in business environments
I didn't uninstall the previous version when I upgraded (at that time I had Outlook 2016), and it worked just fine. I recently had to have my computer replaced, and the company still allowed us to put Outlook Classic on it (though they installed the New Outlook when then set it up), and Classic works just fine. I did have to add my accounts back in, but with my computer being replaced I would have to do that with New Outlook, anyway.