diff --git a/scripts/plot.py b/scripts/plot.py
index 158d94e0..fc3f12d2 100755
--- a/scripts/plot.py
+++ b/scripts/plot.py
@@ -1531,7 +1531,10 @@ def main_(ring, csv_paths, *,
                         if name in datalabels_
                         else ','.join(name))
 
-            if label:
+            # append and merge identical labels
+            if not label:
+                continue
+            if (label, datacolors_[name]) not in legend_:
                 legend_.append((label, datacolors_[name]))
                 legend_width = max(legend_width, len(label)+1)
 
diff --git a/scripts/plotmpl.py b/scripts/plotmpl.py
index 43f318cb..b3fe3f59 100755
--- a/scripts/plotmpl.py
+++ b/scripts/plotmpl.py
@@ -1334,14 +1334,26 @@ def main(csv_paths, output, *,
             legend[l] = h
     # sort in dataset order
     legend_ = []
+    legend__ = set()
     for i, name in enumerate(datasets_.keys()):
+        if name in datalabels_ and not datalabels_[name]:
+            continue
+
         name_ = ','.join(name)
-        if name_ in legend:
-            if name in datalabels_:
-                if datalabels_[name]:
-                    legend_.append((datalabels_[name], legend[name_]))
-            else:
-                legend_.append((name_, legend[name_]))
+        if name_ not in legend:
+            continue
+
+        if name in datalabels_:
+            label = datalabels_[name]
+        else:
+            label = name_
+
+        # append and merge identical labels
+        if not label:
+            continue
+        if (label, datacolors_[name], dataformats_[name]) not in legend__:
+            legend_.append((label, legend[name_]))
+            legend__.add((label, datacolors_[name], dataformats_[name]))
     legend = legend_
 
     if legend_right: