What does it mean if TXID and WTXID are the same?
The wtxid and txid are the same if and only if the transaction does not contain any segwit inputs. The wtxid is the hash of the entire transaction including all segwit data (i.e. the marker and flag bytes and the witness fields themselves). The txid is the hash of the non-segwit parts of the transaction. Because a transaction that does not have any segwit inputs does not have any segwit data at all, both the wtxid and txid hash the same data, so they are the same.