Rephrase whatsnew entry, name copy of self result rather than frame

Author: Marco Gorelli

doc/source/whatsnew/v1.0.0.rst

@@ -143,7 +143,7 @@ Indexing
 ^^^^^^^^
 
 - Bug in assignment using a reverse slicer (:issue:`26939`)
-- Frame gets duplicated when exploding a single column and there are duplicates in the index (:issue:`28010`)
+- Bug in :meth:`DataFrame.explode` would duplicate frame in the presence of duplicates in the index (:issue:`28010`)
 
 Missing
 ^^^^^^^

pandas/core/frame.py

@@ -6259,9 +6259,9 @@ def explode(self, column: Union[str, Tuple]) -> "DataFrame":
         if not self.columns.is_unique:
             raise ValueError("columns must be unique")
 
-        frame = self.copy()
-        exploded_col = frame.pop(column).reset_index(drop=True).explode()
-        result = frame.reset_index().join(exploded_col)
+        result = self.copy()
+        exploded_col = result.pop(column).reset_index(drop=True).explode()
+        result = result.reset_index().join(exploded_col)
 
         if isinstance(self.index, ABCMultiIndex):
             result.index = pandas.MultiIndex.from_frame(