For approximate join queries, duplicate column names in two tables are not allowed.

[ttt-77]

https://github.com/ddkang/aidb/blob/bef78d2339b0f6f654467f58651f80a21ae1f2da/aidb/engine/approx_aggregate_join_engine.py#L215-L218 The program utilizes a column name as a key since the dataframe retrieved from the database use this column name instead of the format {table}.{column}. Consequently, when two dataframes are concatenated, duplicate column names may appear in the merged dataframe if the same column names exist across both tables.