You could call both procedures at once in the PL/SQL Block of your TOracleQuery instance, and pass the CLOB value to both procedures. This would minimize the number of calls, network traffic, and network roundtrips.

You would need to create the CLOB with the CreateTemporary constructor though, and write the CLOB data before calling the PL/SQL Block. The returning clause can be omitted from the update statement, and all columns can be written directly.