We are in a similar situation. Originally, we were booked a flight on a Norwegian Airlines flight from Copehagen to Dublin which was suppose to depart at 12:30 PM. Unfotunately, that flight was cancelled and we were placed on a 8:00 AM flight on June 24th. Our only choices was to change it to a 10:00 AM departure or an evening departure that day.
We decided to try for the 10:00 AM departure on Norwegian Airlines as we would not reach our Hotel in Southwest Ireland until the next day if we took the evening flight.
I figure we have no better than a 50 percent chance of making that 10 AM flight after athe cruise. So we booked a 15:35 flight on Ryan Air for insurance in case we case we cannot make the 10:00 AM time with Norwegian air.
Thus we now have 2 flights to the same destianation that day. I only did that because the Ryan Air flight was a low cost alternative.
We will first try to catch the 10:00 AM flight with Norwegian Air. But if we can't make it, we will take the 15:35 Ryan Air flight instead.
All of this makes it quite confusing as when we should arrive in Dublin to pick up our rental car.