неправильный синтаксис; используйте один из них:
SQL> create table academic_session
2 (session_id number,
3 session_name varchar2(20));
Table created.
SQL> insert into academic_session (session_id, session_name)
2 select 200, 'fall session' from dual union all
3 select 300, 'summer session' from dual;
2 rows created.
SQL> insert all
2 into academic_session (session_id, session_name)
3 values (400, 'spring session')
4 into academic_session (session_id, session_name)
5 values (500, 'winter session')
6 select * from dual;
2 rows created.
SQL>