fdo#77307: Compare external formula tokens correctly.

To avoid different external (add-in) tokens from being evaluated equal.

Change-Id: If78187901bdca7fe0da50442b0bb66e0650dc70f

sc/source/core/data/formulacell.cxx

@@ -3641,6 +3641,15 @@ ScFormulaCell::CompareState ScFormulaCell::CompareByTokenArray( ScFormulaCell& r
                     return NotEqual;
             }
             break;
+            case formula::svExternal:
+            {
+                if (pThisTok->GetExternal() != pOtherTok->GetExternal())
+                    return NotEqual;
+
+                if (pThisTok->GetByte() != pOtherTok->GetByte())
+                    return NotEqual;
+            }
+            break;
             default:
                 ;
         }