I'm not sure I'm following you, but my guess is that you're looking at two devices here; one is the emitter coming out of the system processor and the other is the IR receiver (allowing the source to be placed behind a wall mounted display) for the source, and that the two are taped together to allow them to talk to each other. The source may have an IR window on the front of it, but would mean an emitter on the front of the rack which a) could eventually fall off and b) may not look as good.
Added: I shouldn't have answered so early in the morning as I realized you came to the same conclusion as I did about what it was. I would think that the receiving end needs to be active in this situation, otherwise you would just have a dead IR receiver. But it would be easy enough to try without.
Last edited by trevcda on August 18, 2016 12:42.