This report is designed to show the history of the equipments within the given period of time.
If you give current date, it will give the details of the equipment. If you change the same equipment twice in same date (current date), then of course, you will get the 2 rows for same equipment.
If you give date range, then all the histories will be displayed for that equipment.
What is the reason user wants to see equipment list with only one time equipment for the specified date range?? Then let them give specific date.