The Setada Cup currently includes four matches with hosts from Ireland and guests from Northern Ireland. In all four of these matches, the guests are given from simple (3,40) to hot (7,50) underdogs. I do not know how much Irish is different from Northern Irish football, but what I see is that the Irish are in preparation while the others are in the middle of the season. This is basically the first official season for the Irish teams. So I give a "readiness" bonus to the guests.
Looking for the rest of the data I saw that Cork (who finished somewhere in the middle of last year's championship) sold first (11) and second (9) scorers, while today he has three injured. On the other hand, I see that Cliftonville is at the top of its league, with a 22b difference from the second! It has two goal scorers with 28/20 one and with the other 24/16. The coach stated that he will make changes in moderation, putting mostly key ones in order to get a positive result in view of the rematch. So judging by these data I find 3,40 big for the double.