It's simply a courtesy message, I'm sure some airlines wouldn't do this but some people go to the airport and look up flights by flight number for their departure, especially as some destinations have say 2 flights within a short space of time, so it stops confusion and means passengers have no excuse if they are late checking in or late to their departure gate, this way EI have passed the info onto the PAX so it's not EI.s fault if your late because you had the wrong flight number. I see your point but I also see why they did it. Believe me, from experience those pax arriving late to both gates and check in will use any excuse in the dictionary, some of them are so unbelievable and u know they are untrue u try your best to maybe get them on the flight or accommodate them as best as possible because of such a legiondary excuse and just for making you laugh. Half the time if they don't get on they will turn round and say it was worth a ret making up that excuse.