With the current update of the Ikea Tradfri iOS App it is now possible to use two control units in one room.

A control device is a switch or dimmer or other input device. Up to now, only one of these devices could be assigned per room, so you couldn’t put one switch at one end of the couch and a second switch at the other to control the same lamp in the room, you always had to create a new room. So this is finally possible.

It’s nice to see that Ikea is still working on the software. The system is otherwise quite simple and clear, but it is also very inexpensive.