Live ORACLE

DECLARE
TYPE empcurtyp IS REF CURSOR;
c1  EMPCURTYP;
c2  EMPCURTYP;
PROCEDURE Get_emp_data
    (emp_cv1  IN OUT EMPCURTYP,
     emp_cv2  IN OUT EMPCURTYP)
IS
 emp_rec  employees%ROWTYPE;
BEGIN
 OPEN emp_cv1 FOR
   SELECT *
   FROM   employees;
 emp_cv2 := emp_cv1;
 FETCH emp_cv1 INTO emp_rec; -- fetches first row
 FETCH emp_cv1 INTO emp_rec; -- fetches second row
 FETCH emp_cv2 INTO emp_rec; -- fetches third row
 CLOSE emp_cv1;
 dbms_output.Put_line('The following raises an invalid cursor');
-- FETCH emp_cv2 INTO emp_rec; raises invalid cursor when get_emp_data is called
END;
BEGIN
Get_emp_data(c1,c2);
END;
/  

The following raises an invalid cursor

PL/SQL procedure successfully completed.

Aliasing from Assigning Cursor Variables to Same Work Area