Don't add duplicate etch lines.

EtchBendLines/Extensions.cs

@@ -13,6 +13,11 @@ namespace EtchBendLines
             return new Vector2(pt.X, pt.Y);
         }
 
+        public static bool IsEqualTo(this Vector3 pt, Vector3 pt1)
+        {
+            return pt.X.IsEqualTo(pt1.X) && pt.Y.IsEqualTo(pt1.Y) && pt.Z.IsEqualTo(pt1.Z);
+        }
+
         public static bool IsVertical(this Line line)
         {
             return line.StartPoint.X == line.EndPoint.X;

EtchBendLines/Program.cs

@@ -98,7 +98,20 @@ namespace EtchBendLines
             foreach (var bendline in upBends)
             {
 				var etchLines = bendline.GetEtchLines(ETCH_LENGTH);
-				dxf.AddEntity(etchLines);
+
+                foreach (var etchLine in etchLines)
+                {
+                    var existing = dxf.Lines.FirstOrDefault(l => l.StartPoint.IsEqualTo(etchLine.StartPoint));
+
+                    if (existing != null)
+                    {
+                        // ensure the layer is correct and skip adding the etch line since it already exists.
+                        existing.Layer = etchLine.Layer;
+                        continue;
+                    }
+
+                    dxf.AddEntity(etchLine);
+                }
             }
 
             dxf.Save(filePath);