diff --git a/CHANGES.md b/CHANGES.md
index 987bef965dad..dcf36e2a7773 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -23,6 +23,7 @@ Change Log
 * Fixed a bug causing crashes with custom vertex attributes on `Geometry` crossing the IDL. Attributes will be barycentrically interpolated. [#6644](https://github.com/AnalyticalGraphicsInc/cesium/pull/6644)
 * Fixed a bug causing Point Cloud tiles with unsigned int batch-ids to not load. [#6666](https://github.com/AnalyticalGraphicsInc/cesium/pull/6666)
 * Fixed a bug with Draco encoded i3dm tiles, and loading two Draco models with the same url. [#6668](https://github.com/AnalyticalGraphicsInc/cesium/issues/6668)
+* Fixed a bug caused by creating a polygon with positions at the same longitude/latitude position but different heights [#6731](https://github.com/AnalyticalGraphicsInc/cesium/pull/6731)
 * Fixed terrain clipping when the camera was close to flat terrain and was using logarithmic depth. [#6701](https://github.com/AnalyticalGraphicsInc/cesium/pull/6701)
 * Fixed KML bug that constantly requested the same image if it failed to load. [#6710](https://github.com/AnalyticalGraphicsInc/cesium/pull/6710)
 * Improved billboard and label rendering so they no longer sink into terrain when clamped to ground. [#6621](https://github.com/AnalyticalGraphicsInc/cesium/pull/6621)
diff --git a/Source/Core/PolygonGeometryLibrary.js b/Source/Core/PolygonGeometryLibrary.js
index c1f836661a62..ba6cf5426414 100644
--- a/Source/Core/PolygonGeometryLibrary.js
+++ b/Source/Core/PolygonGeometryLibrary.js
@@ -218,8 +218,10 @@ define([
             var holes = outerNode.holes;
 
             var i;
+            var length;
             if (!perPositionHeight) {
-                for (i = 0; i < outerRing.length; i++) {
+                length = outerRing.length;
+                for (i = 0; i < length; i++) {
                     ellipsoid.scaleToGeodeticSurface(outerRing[i], outerRing[i]);
                 }
             }
@@ -247,7 +249,8 @@ define([
                 var hole = holes[i];
                 var holePositions = hole.positions;
                 if (!perPositionHeight) {
-                    for (j = 0; j < holePositions.length; ++j) {
+                    length = holePositions.length;
+                    for (j = 0; j < length; ++j) {
                         ellipsoid.scaleToGeodeticSurface(holePositions[j], holePositions[j]);
                     }
                 }
diff --git a/Source/Core/PolygonOutlineGeometry.js b/Source/Core/PolygonOutlineGeometry.js
index 0caac11696ad..95a854cd1f65 100644
--- a/Source/Core/PolygonOutlineGeometry.js
+++ b/Source/Core/PolygonOutlineGeometry.js
@@ -484,11 +484,13 @@ define([
         queue.enqueue(polygonHierarchy);
         var i;
         var j;
+        var length;
         while (queue.length !== 0) {
             var outerNode = queue.dequeue();
             var outerRing = outerNode.positions;
             if (!perPositionHeight) {
-                for (i = 0; i < outerRing.length; i++) {
+                length = outerRing.length;
+                for (i = 0; i < length; i++) {
                     ellipsoid.scaleToGeodeticSurface(outerRing[i], outerRing[i]);
                 }
             }
@@ -503,7 +505,8 @@ define([
                 var hole = outerNode.holes[i];
                 var holePositions = hole.positions;
                 if (!perPositionHeight) {
-                    for (j = 0; j < holePositions.length; ++j) {
+                    length = holePositions.length;
+                    for (j = 0; j < length; ++j) {
                         ellipsoid.scaleToGeodeticSurface(holePositions[j], holePositions[j]);
                     }
                 }
@@ -566,7 +569,7 @@ define([
                 geometryInstance.geometry.attributes.position.values = PolygonPipeline.scaleToGeodeticHeight(geometryInstance.geometry.attributes.position.values, height, ellipsoid, !perPositionHeight);
 
                 if (defined(polygonGeometry._offsetAttribute)) {
-                    var length = geometryInstance.geometry.attributes.position.values.length;
+                    length = geometryInstance.geometry.attributes.position.values.length;
                     var applyOffset = new Uint8Array(length / 3);
                     offsetValue = polygonGeometry._offsetAttribute === GeometryOffsetAttribute.NONE ? 0 : 1;
                     arrayFill(applyOffset, offsetValue);
diff --git a/Specs/Core/PolygonGeometrySpec.js b/Specs/Core/PolygonGeometrySpec.js
index 4a6f90318759..f97032f86453 100644
--- a/Specs/Core/PolygonGeometrySpec.js
+++ b/Specs/Core/PolygonGeometrySpec.js
@@ -139,7 +139,7 @@ defineSuite([
         };
 
         var geometry = PolygonGeometry.createGeometry(new PolygonGeometry({ polygonHierarchy : hierarchy, perPositionHeight: true }));
-        expect(geometry).not.toBeUndefined();
+        expect(geometry).toBeDefined();
     });
 
     it('computes positions', function() {
diff --git a/Specs/Core/PolygonOutlineGeometrySpec.js b/Specs/Core/PolygonOutlineGeometrySpec.js
index c3a76589dae6..013329d16c0b 100644
--- a/Specs/Core/PolygonOutlineGeometrySpec.js
+++ b/Specs/Core/PolygonOutlineGeometrySpec.js
@@ -133,7 +133,7 @@ defineSuite([
         };
 
         var geometry = PolygonOutlineGeometry.createGeometry(new PolygonOutlineGeometry({ polygonHierarchy : hierarchy, perPositionHeight: true }));
-        expect(geometry).not.toBeUndefined();
+        expect(geometry).toBeDefined();
     });
 
     it('computes positions', function() {