It's dual conversion, and it is not getting two signals.

The way that receivers work mean that they convert your Tx signal to a mere 455khz signal. The problem is that the Rx hears two Tx, one that is 455khz above it and one that is 455khz below it. One of those is your Tx and the other comes from something else. That's bad news. It's called single conversion. Most of the time it is not a problem, it only causes a problem if there is another signal on that other frequency. Some other frequencies which are multiples or divisions of your frequency can also cause these images in the Rx. Dual conversion is a way of getting over that problem, it converts your signal first to 10.7Mhz then down to 455 khz. That stops the images caused by the other signals. It's an addded bit of protection so it is worth having. Most brands make plenty of dual conversion Rx, JR mostly ignores it in favour of its ABC&W which is not as good as dual conversion.

Note that dual conversion blocks image caused by signals from specific other frequencies than yours. It does not protect you from signals on your frequency or from bleed over from poorly tuned Tx on adjacent frequecies etc.

H