diff --git a/src/ifcgeom/kernels/opencascade/faceset_helper.cpp b/src/ifcgeom/kernels/opencascade/faceset_helper.cpp
index b139c521c8..ee13448d90 100644
--- a/src/ifcgeom/kernels/opencascade/faceset_helper.cpp
+++ b/src/ifcgeom/kernels/opencascade/faceset_helper.cpp
@@ -108,7 +108,7 @@ ifcopenshell::geom::open_cascade_kernel::faceset_helper::faceset_helper(
 
 		vertex_mapping_.clear();
 		duplicates_.clear();
-		duplicate_skips_remaining_.clear();
+		duplicate_identities_built_.clear();
 
 		edge_use.clear();
 
@@ -176,7 +176,6 @@ ifcopenshell::geom::open_cascade_kernel::faceset_helper::faceset_helper(
 			if (edge_sets.find(edge_set_key) != edge_sets.end()) {
 				duplicate_faces++;
 				duplicates_.insert(loop->identity());
-				duplicate_skips_remaining_[loop->identity()]++;
 				continue;
 			}
             edge_sets.insert(edge_set_key);
@@ -253,11 +252,13 @@ bool ifcopenshell::geom::open_cascade_kernel::faceset_helper::wire(const ifcopen
 }
 
 bool ifcopenshell::geom::open_cascade_kernel::faceset_helper::wires(const ifcopenshell::geom::taxonomy::loop::ptr loop, NCollection_List<TopoDS_Shape>& wires) {
-	// Skip only the redundant occurrences, keep one copy of the face.
-	auto it = duplicate_skips_remaining_.find(loop->identity());
-	if (it != duplicate_skips_remaining_.end() && it->second > 0) {
-		--it->second;
-		return false;
+	// A loop whose edge set duplicates another's is skipped. When the duplicates
+	// share one identity (the same IfcFace listed repeatedly, #418), set semantics
+	// keep exactly one copy: the first occurrence builds, the rest are skipped.
+	if (duplicates_.find(loop->identity()) != duplicates_.end()) {
+		if (!duplicate_identities_built_.insert(loop->identity()).second) {
+			return false;
+		}
 	}
 	TopoDS_Wire wire;
 	BRep_Builder builder;
diff --git a/src/ifcgeom/kernels/opencascade/opencascade_kernel.h b/src/ifcgeom/kernels/opencascade/opencascade_kernel.h
index 6350f92b22..8fc43f8f23 100644
--- a/src/ifcgeom/kernels/opencascade/opencascade_kernel.h
+++ b/src/ifcgeom/kernels/opencascade/opencascade_kernel.h
@@ -86,7 +86,7 @@ private:
 	private:
 		open_cascade_kernel* kernel_;
 		std::set<int> duplicates_;
-		std::map<int, int> duplicate_skips_remaining_;
+		std::set<int> duplicate_identities_built_;
 		std::map<int, int> vertex_mapping_;
 		std::map<std::pair<int, int>, TopoDS_Edge> edges_;
 		double eps_;