Just stumbled upon this in a unit test (happens with two and three items of a content type).
when i supply a sort_order for a query i get different results. one brain is missing, another one gets duplicated:
>>> [brain.id for brain in catalog.evalAdvancedQuery(qry)]
>>> [brain.id for brain in catalog.evalAdvancedQuery(qry, (('start', 'asc'),))]
tried with advancedquery 3.0.2, 3.0.3, 3.0.4
@dieter do you have any idea why this could happen?