It doesn't seem as though renaming the title of a modern dashboard is possible. Anyone know a way to do it without duplicating/deleting old page? Since it doesn't use the title in the url it seems like it should be possible.
Currently the only way to do this is as you say - duplicate and delete the old dashboard.
https://thwack.solarwinds.com/t5/The-Orion-Platform-Documents/Orion-Platform-2020-2-Modern-Dashboards/tac-p/595865/highlight/true#M196
