diff --git a/sksurgeryimage/calibration/dotty_grid_point_detector.py b/sksurgeryimage/calibration/dotty_grid_point_detector.py
index b009753..06decfe 100644
--- a/sksurgeryimage/calibration/dotty_grid_point_detector.py
+++ b/sksurgeryimage/calibration/dotty_grid_point_detector.py
@@ -356,6 +356,16 @@ def _internal_get_points(self, image):
                 img_points[counter][0] = distorted_x
                 img_points[counter][1] = distorted_y
 
+            unique_ids, unique_idxs, counts = \
+                np.unique(indexes, return_index=True, return_counts=True)
+
+            unique_ids = unique_ids[counts==1]
+            unique_idxs = unique_idxs[counts==1]
+
+            indexes = indexes[unique_idxs]
+            object_points = object_points[unique_idxs]
+            img_points = img_points[unique_idxs]
+
             return indexes, object_points, img_points
 
         # If we didn't find all points, of the fit was poor,
diff --git a/tests/calibration/test_dotty_grid_detector_metal.py b/tests/calibration/test_dotty_grid_detector_metal.py
index e355612..3041c79 100644
--- a/tests/calibration/test_dotty_grid_detector_metal.py
+++ b/tests/calibration/test_dotty_grid_detector_metal.py
@@ -27,8 +27,7 @@ def test_metal_1a(setup_dotty_metal_model_OR):
     number_of_points = tdgu.__check_real_OR_image(model_points,
                                                   img_path,
                                                   'tests/data/calib-ucl-circles/10_54_44/viking.calib.left.intrinsics.txt',
-                                                  'tests/data/calib-ucl-circles/10_54_44/viking.calib.left.distortion.txt',
-                                                  True
+                                                  'tests/data/calib-ucl-circles/10_54_44/viking.calib.left.distortion.txt'
                                                   )
 
     assert (326 == number_of_points)
diff --git a/tests/calibration/test_dotty_grid_point_detector.py b/tests/calibration/test_dotty_grid_point_detector.py
index 69d8e43..2396294 100644
--- a/tests/calibration/test_dotty_grid_point_detector.py
+++ b/tests/calibration/test_dotty_grid_point_detector.py
@@ -117,7 +117,7 @@ def test_dotty_uncalibrated_5(setup_dotty_calibration_model):
                                           'tests/data/calib-ucl-circles/calib.left.intrinsics.txt',
                                           'tests/data/calib-ucl-circles/calib.left.distortion.txt',
                                           )
-    assert(357 == number_of_points)
+    assert(355 == number_of_points)
 
 
 def test_dotty_uncalibrated_6(setup_dotty_calibration_model):
@@ -127,7 +127,7 @@ def test_dotty_uncalibrated_6(setup_dotty_calibration_model):
                                           'tests/data/calib-ucl-circles/calib.right.intrinsics.txt',
                                           'tests/data/calib-ucl-circles/calib.right.distortion.txt',
                                           )
-    assert(356 == number_of_points)
+    assert(354 == number_of_points)
 
 
 def test_dotty_uncalibrated_7(setup_dotty_calibration_model):
@@ -555,3 +555,14 @@ def test_metal_6(setup_dotty_metal_model):
                                           )
     assert (224 == number_of_points)
 
+def test_all_unique_points_detected(setup_dotty_metal_model_OR):
+    # Test an image on which the dot detector was previously detecting multiple instances of the same dot.
+    model_points = setup_dotty_metal_model_OR
+
+    number_of_points = tdgu.__check_real_OR_image(model_points,
+                                          'tests/data/calib-ucl-circles/detecting_same_point_twice_dots.png',
+                                          'tests/data/calib-ucl-circles/10_54_44/viking.calib.left.intrinsics.txt',
+                                          'tests/data/calib-ucl-circles/10_54_44/viking.calib.right.distortion.txt'
+                                          )
+
+    assert(number_of_points) == 366
diff --git a/tests/calibration/test_dotty_grid_utils.py b/tests/calibration/test_dotty_grid_utils.py
index 7febf4a..4df7d6d 100644
--- a/tests/calibration/test_dotty_grid_utils.py
+++ b/tests/calibration/test_dotty_grid_utils.py
@@ -64,7 +64,6 @@ def __check_real_OR_image(model_points,
                          image_file_name,
                          intrinsics_file_name,
                          distortion_file_name,
-                         is_metal=False
                          ):
     logging.basicConfig(level=logging.DEBUG)
     image = cv2.imread(image_file_name)
@@ -73,9 +72,7 @@ def __check_real_OR_image(model_points,
 
     size = (2600, 1900)
     fiducials = [133, 141, 308, 316]
-    if is_metal:
-        fiducials = [133, 141, 308, 316]
-        size = (2600, 1900)
+
 
     detector = DottyGridPointDetector(model_points,
                                       fiducials,
diff --git a/tests/data/calib-ucl-circles/detecting_same_point_twice_dots.png b/tests/data/calib-ucl-circles/detecting_same_point_twice_dots.png
new file mode 100644
index 0000000..87f54b3
Binary files /dev/null and b/tests/data/calib-ucl-circles/detecting_same_point_twice_dots.png differ