I reproduced the situation for 5.1.4.Final. You can check the test org.hibernate.bugs.QueryGenerationTestCase#testRedundantSqlJoins in my repo https://github.com/stasal/hibernate-tests/ in branch hibernate-5.1

Though I'm not sure if it is the same problem, but the redundant left join is generated in this case too (see resulting SQL, there should not be left joins to PotDates table) resultng query.sql