I think this is a cache issue since it is resolved after a refresh but its just annoying to deal with.
you are in the "https://railway.com/project/project_id" page, you make a deplyoment, you go back to the the "https://railway.com/dashboard" now there is 2 projects the same id, the same thing, you do a refresh now it is only 1, I suspect the new deployment created a new item in the UI, and it just added to the cache, didn't swap out the cache hence on reload it fetches fresh and now there is no duplicates.