Use caution, should you decide to acquire a second radio controller. I believe the firmware on the second slave controller should closely match that which is loaded on the Master should you not want to upgrade to a newer version on both radios. I also believe you may only be permitted to drop back (1) firmware version on either radio to match them. POI, Some folks simply don't wish to update to the latest firmware for fear of various flight restrictions and such, and so is why matching the secondary Slave radio firmware to the Master is an important concern.
I had found a previously owned and modified controller with a long distance DBS antenna and a secondary 5.8 Ghz antenna as shown, and have not found any interference video or otherwise when controlling the camera with the secondary radio controller.
Hope this info. helps.