The Query & Output Processing job ran pending query and output schedule records for the past when you include a specific schedule date on the job, but no record seq.
Query & Output Processing is designed so that if you do not include a record seq along with the schedule date, then it will run any pending query and output schedule records with a schedule date equal to or before the schedule date on the Query & Output Processing job. You can still include a query name or group name to restrict what it runs, but if you do not include a record seq along with the schedule date, it will run all pending records that meet the criteria for that schedule date and before, not just for that schedule date.
To get it to run records for just a given schedule date, you must include a record seq as well, normally of 1. So to get all queries scheduled for just a specific date to run, you would include just the schedule date and a record seq 1.