Double bookings usually happen when scheduling lives in a spreadsheet or a whiteboard and two people allocate the same asset without seeing each other's changes. StayOnHire's job calendar shows every asset's live availability in one shared view, so a conflict is visible before the job is confirmed, not after a customer turns up to an already-booked machine.
Assets can also be allocated by position or category rather than a specific unit, so you're not locked into one asset until it's actually needed.