diff --git a/src/wireviz/wv_harness.py b/src/wireviz/wv_harness.py
index 43acc5b..90d538f 100644
--- a/src/wireviz/wv_harness.py
+++ b/src/wireviz/wv_harness.py
@@ -52,7 +52,7 @@ class Harness:
     def name(self) -> str:
         pn = self.metadata.get("pn", "")
         output_name = self.metadata["output_name"]
-        if pn:
+        if pn and pn not in output_name:
             return f"{pn}-{output_name}"
         else:
             return output_name