SQL> declare
  2     cursor c1 is select * from dual;
  3     cursor c1 (in_1_p in number) is select * from dual;
  4     cursor c1 (in_1_p in number, in_2_p in number) is select * from dual;
  5  begin null;
  6  end;
  7  /

PL/SQL procedure successfully completed.

SQL> declare
  2     cursor c1 is select * from dual;
  3     cursor c1 (in_1_p in number) is select * from dual;
  4     cursor c1 (in_1_p in number, in_2_p in number) is select * from dual;
  5  
  6     v1 varchar2(1);
  7  begin null;
  8     open c1;
  9     open c1 (1);
 10     open c1 (1,2);
 11  end;
 12  /
   open c1;
   *
ERROR at line 8:
ORA-06550: line 8, column 4:
PLS-00307: too many declarations of 'C1' match this call
ORA-06550: line 8, column 4:
PL/SQL: SQL Statement ignored
ORA-06550: line 9, column 9:
PLS-00307: too many declarations of 'C1' match this call
ORA-06550: line 9, column 4:
PL/SQL: SQL Statement ignored
ORA-06550: line 10, column 9:
PLS-00307: too many declarations of 'C1' match this call
ORA-06550: line 10, column 4:
PL/SQL: SQL Statement ignored