Getting a formatter error when trying to format text case with 2 identical value (4333008)

Getting a formatter error when trying to format text case with 2 identical value.
See example below:

DECLARE
grade CHAR(1);
BEGIN
grade := 'B';

CASE grade
WHEN 'A' THEN DBMS_OUTPUT.PUT_LINE('Excellent');
WHEN 'A' THEN DBMS_OUTPUT.PUT_LINE('Very Good');
WHEN 'C' THEN DBMS_OUTPUT.PUT_LINE('Good');
WHEN 'D' THEN DBMS_OUTPUT.PUT_LINE('Fair');
WHEN 'F' THEN DBMS_OUTPUT.PUT_LINE('Poor');
ELSE DBMS_OUTPUT.PUT_LINE('No such grade');
END CASE;
END;
/

When trying to format the code it says :15:31:25 ERROR line 8, col 5, ending_line 8, ending_col 52: Duplicated case entry found: 'A'

The problem is that piece of code:

WHEN 'A' THEN DBMS_OUTPUT.PUT_LINE('Excellent');
WHEN 'A' THEN DBMS_OUTPUT.PUT_LINE('Very Good');

WORKAROUND

None

STATUS

Waiting for fix in a future release SQL Navigator for Oracle