Double bookings are being allowed

I have approved a reservation from the 4th of Aug thru the 8th of Aug, yet someone else just booked the same unit from the 7th of August to the 10th of August. The resources count is set at 1, so this should not be allowed to go through as pending. Am I missing something in my settings?

Please send me admin and FTP access to support@easyreservations.org
Can you always reserve over another reservation or just in edge cases?
Regards