I searched the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800. Unless the county is known, there is AT LEAST a 35% chance the ancestor's rcds aren't in the database.
Note - Queens Co. (now Laois) isn't in this database.
For Roger Mooney B ???? somewhere in Ireland, I found 3 B rcds: 1778 Dublin, 1809 Meath, and 1886 Dublin.
For Brid(get) Marran (+79 variants) ditto, I found 2 rcds that MIGHT fit your timeline: 1790 Meath, and 1804 Dublin.
Will let you play with the database to try to find common marriage rcds (same yr, same county, same parish).
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.