Problem:
Error: PLS-00323: subprogram or cursor ‘UPD_COSTELEMENTX’ is declared in a package specification and must be defined in the package body
Error: PLS-00410: duplicate fields in RECORD,TABLE or argument list are not permitted
_Error: PL/SQL: Item ignored  _

procedure UPD_COSTELEMENT (p_commit in number, p_out_msg out varchar2) is
(…)
    l_logfile_name            varchar2(250);
    **p_out_msg              varchar2(4000);   **
    lf                                 utl_file.file_type;
 
    begin
        dbms_output.enable(null);
_(…) _

Cause:

Double initialization of the variable p_out_msg.