Andreas Noeske posted this on a number of newsgroups just now. Never occured to me and maybe I am slow and this has been talked about elsewhere but looks like the same bird has gone from Ireland to Germany and now Denmark!
Doing a google search and Mourning Doves do seem to have slightly different dark markings on the wings from bird to bird so does look like it's the same bird. I guess maybe not all these nearctic passerine vagrants are on their last legs. Astonishing that Europe is so well covered that it got found so many times. Is it likely that the Dawlish Long-billed Murrelet was the same bird found in Romania 4 weeks later?