Exemplary embodiments of merchandise display security devices including anti-theft features for preventing theft of an item of merchandise being displayed in a display area of a retail store are shown and described. The security devices provide a dual alarm merchandise security system including an alarm unit attached to the item of merchandise and electrically and mechanically connected to a fixed unit that is attached to a fixed support within the display area. The alarm unit and the fixed unit each include an alarm that is activated by a control circuit upon predetermined alarm conditions. A breakaway cable interconnects the alarm unit and the fixed unit and defines a sense loop therebetween. In one embodiment, the fixed unit is a display stand and the alarm unit is a sensor configured to be removably supported on the display stand.