A dispensing device includes a controller and first and second actuators coupled to the controller and adapted to actuate first and second containers, respectively, to dispense volatile material therefrom. The device further includes a sensor coupled to the controller for detecting an environmental condition. The controller is configured to operate in a first period during which the first and second actuators are inactive, in a second period during which the first actuator is controlled to periodically actuate the first container at a first frequency to dispense volatile material therefrom, and in a third period during which the second actuator is controlled to periodically actuate the second container at a second frequency to dispense volatile material therefrom. If the sensor has detected the environmental condition, the controller is configured to control the first and/or second actuators to periodically actuate the first and/or second containers, respectively, during a fourth period at a third frequency different than the first and second frequencies to dispense volatile material therefrom.