This jibes with my experience. When I was confirmed three years ago (as an adult), most of my OCIA classmates kept their own names as their confirmation names - Scott, Courtney, etc. I took “Gilbert” as my name, which is a saint’s name, but my instructors were well aware that I took it in honor of G.K. Chesterton. The priest never asked about it, nor any of my classmates’ monikers.
(OCIA - the Order of Christian Initiation of Adults - the classes and rites an adult goes through to be confirmed in the Roman Catholic Church).