looking for marriage of james hughes to margaret hughes on on 10thNovember 1856 - this was recorded on their childrens birth certificate in scotland . On Margarets death certificate her maiden name was recorded as Hughes not sure if that is correct.
Catherine:
You did not mention the religious denomination of James and Margaret. Roots Ireland www.rootsireland.ie has RC records for Dungannon parish back to 1821 but they do not have C of I or Presbyterian records for Dungannon. Roots does have an 1855 marriage of a James Hughes to a wife named Margaret although not in Dungannon. James Hughes is fairly common in Tyrone so maybe this is another couple. Roots is a pay site to see the actual data on a record.
Roger McDonnell
I suspect the marriage was RC (because I can't see it in the indexes to non RC marriages around that time). RC marriages weren?t included in the Irish civil records till 1864. However you might be able to trace it in the parish records. Try the rootsireland site. They have a James Hughes who married a Margaret in 1855 in Tyrone. Or it might be worth checking Dungannon RC marriages records in PRONI in Belfast (where a copy is kept).
Don't expect too much frrom the records if you find them. RC marriage records from that period usually just have the couples names and their 2 witnesses.