There are, according to maps of the area I have seen, parts of Scotland that carry the name Kilduff. The estate of the Earl of Athelstaneford (outside Edinburgh, Scotland) carries many locations with the name Kilduff. Strangely, no Kilduffs are present today which may link in with actual history and the Highland Clearances. However, any presence is (by comparison) recent history as the name definitely originates in Ireland. The largest localised presence of which exists in Athlone today. This appears to be the heartland of the clan.