Here are maps for the Kurn's Tower zones. They correctly load in all zones for Kurn's (the 2 instances in Fens and the 4 in Svarni).
I don't know if making a map style specific for each zone is needed? As far as I know, mobs are more or less in the same spot for each and apart from quests in the original zone, there isn't anything really specific to the reuses.
Code:
<ImageStyle Name="exp04_dun_kurns_tower_0" displayname="Kurn's Tower Level 1" zonerect="-205, -215, 209, 265" heightmax="100">
<ImageFrame Source="images/maps/map_exp04_dun_kurns_tower_0.dds" SourceRect="0,0,436,506" />
</ImageStyle>
<ImageStyle Name="exp04_dun_kurns_tower_1" displayname="Kurn's Tower Level 2" zonerect="-205, -215, 209, 265" heightmin="100" heightmax="230">
<ImageFrame Source="images/maps/map_exp04_dun_kurns_tower_1.dds" SourceRect="0,0,436,506" />
</ImageStyle>
<ImageStyle Name="exp04_dun_kurns_tower_2" displayname="Kurn's Tower Level 3" zonerect="-205, -215, 209, 265" heightmin="230" heightmax="350">
<ImageFrame Source="images/maps/map_exp04_dun_kurns_tower_2.dds" SourceRect="0,0,436,506" />
</ImageStyle>
<ImageStyle Name="exp04_dun_kurns_tower_3" displayname="Kurn's Tower Level 4" zonerect="-205, -215, 209, 265" heightmin="350">
<ImageFrame Source="images/maps/map_exp04_dun_kurns_tower_3.dds" SourceRect="0,0,436,506" />
</ImageStyle>