Sorting, when values are equal....

Hello,

If I do something like:

SELECT * FROM sometable ORDER BY somerow DESC LIMIT 1 OFFSET 2;

.. and there are multiple rows in sometable where somerow is identical,
am I assured that the values will always come back in the same order?
..... Or do I need to ensure that a second sort (such as the oid?) is used?

Thanks!

- Greg