Oracle processes duplicate data when creating a primary key

/****************************
V_index is a primary key statement.
Tablename is the table name.
Written by: Wonder
Modified:
****************************/

Create or replace procedure prc_delete (v_index in varchar2, tablename in varchar2) is
V_ SQL varchar2 (2000 );
V_sql1 varchar2 (2000 );

Begin
Execute immediate upper ('truncate table into t_table ');
V_sql1: = upper (replace (v_index, ';', '') | 'exceptions into except_table ');
Begin
Execute immediate v_sql1;
Exception
When others then
NULL;
End;

V_ SQL: = upper ('delete from' | tablename | 'where rowid in (select row_id from effect_table where table_name = ''' |
Tablename | ''')');
Execute immediate v_ SQL;
Execute immediate Replace (v_index ,';','');
Commit;
End prc_delete;