MikeKrebs, Thanks for your reply. My problem was that both duplicate addresses had correct (same) IP addresses. (Before updating to latest xLights, some of my universes, for example (17-24 and 57-60) were on IP address 192.168.1.60 and ran on one controller. After updating, universes 17-24...
I updated my xLights to version 2023 .20 64bit for Windows. After updating, I see that 2 of my 7 controllers show up as duplicate controllers with the same IP, however, both of these controllers show different universe IDs. The "Upload Output" button is grayed out I am NOT able to show lights...