DECLARE
CURSOR C1 IS select e.empno,
       e.ename,
       e.sal,
       d.deptno 
   from emp e,
        dept d 
   where e.deptno = d.deptno
   and not exists(select 1 from emp4 s where 
                         s.empno = e.empno
                         and s.ename = e.ename
                         and s.deptno = d.deptno);
                         
  
       
    TYPE empno_type is table of EMP.EMPNO%TYPE;
    TYPE ename_type is table of emp.ename%TYPE;
    TYPE sal_type is table of emp.sal%type;
    TYPE deptno_type is table of emp.deptno%type;
    
    empnos    empno_type;
    enames   ename_type;
    sals     sal_type;
    deptnos  deptno_type;
    
      v_version number; 
    v_cnt number := 0;
 begin
       OPEN C1;
      LOOP
       
      FETCH C1 BULK COLLECT INTO empnos,enames,sals,deptnos LIMIT 2;
      
      for i in 1..empnos.count
      loop
      BEGIN
      SELECT COUNT(1) 
      into v_cnt
      from emps_tab 
      where empno = empnos(i)
       and ename = enames(i)
       and deptno = deptnos(i);
       
       select  max(version_number)+1 into v_version
       from durchlauf;
       IF v_cnt >= 1 then
      FORALL i in 1..empnos.COUNT
      INSERT INTO EMPS_TAB(empno,ename,sal,deptno,Version_Number,invalid_number)  values(EMPNOS(i),enames(i),sals(i),deptnos(i),v_version,NULL);
      
      UPDATE EMPS_TAB SET INVALID_NUMBER = v_version
      WHERE empno = empnos(i)
       and ename = enames(i)
       and deptno = deptnos(i)
       AND ROWID NOT IN(SELECT MAX(ROWID) FROM emps_tab WHERE empno = empnos(i)
       and ename = enames(i)
       and deptno = deptnos(i));
    ELSE
      FORALL i in 1..empnos.COUNT
      INSERT INTO EMPS_TAB(empno,ename,sal,deptno,Version_Number,invalid_number)  values(EMPNOS(i),enames(i),sals(i),deptnos(i),v_version,NULL);
     END IF;
      EXIT WHEN C1%NOTFOUND;
      EXCEPTION
      WHEN DUP_VAL_ON_INDEX THEN
       dbms_output.put_line(empnos(i)||' '||enames(i)||' '||deptnos(i)||' are duplicate in emps_tab table');
     END;
      END LOOP; 
       end loop;
     close c1;
  commit;
    EXCEPTION
      WHEN OTHERS THEN
        RAISE_APPLICATION_ERROR(-200001,'Exception from Parent Block');
    END;
 

The functioanlity is it will ignore all same records which are coming from cursor and again check for duplicate record in emps_tab table. If cnt >=1 then insert and invalid the invalid number in emps_tab .

AND ROWID NOT IN(SELECT MAX(ROWID) FROM emps_tab WHERE empno = empnos(i)