how can I get two Query calls to return the same reference if it is the same query arguments.

I have tried .setCacheable(true) with <property name="cache.use_query_cache">true</property> but it doesn't work?

The query cache caches only ids. You could change your query to return ids, then use get(id) to get the instance in the session cache.

Check out section 15.9, "Queries by natural identifier", for some optimization tips. If you do change your queries, this will help.