Fix: Add error handling for query with duplicate columns

Author: Xenomorph149

pandas/core/frame.py

@@ -4616,6 +4616,8 @@ def query(self, expr: str, *, inplace: bool = False, **kwargs) -> DataFrame | No
         0  1  10   10
         1  2   8    9
         """
+        if self.columns.duplicated().any():
+            raise ValueError("DataFrame contains duplicate column names.")
         inplace = validate_bool_kwarg(inplace, "inplace")
         if not isinstance(expr, str):
             msg = f"expr must be a string to be evaluated, {type(expr)} given"