Re: IR remote control
The other aspect is beam angle. If you use two, and turn each out from center some the remote's IR will be much more visible across a wide angle. Things cost money, and economics plays a large part in large quantity business decisions. If two narrow angle LEDs give the same beam power but for half the total cost of a high power LED, then it can make sense if your build price with the extra LED doesn't outweigh it.
This was a lot more common with lower power IR LEDs of the 80's and early 90's. I haven't seen much of this since the mid-90's, when the modern type high power LEDs started getting reasonably priced..
More is always better though except for power consumption. When you want a good solid and reliable link, 2 or 3 or 4 makes sense, they're pretty cheap vs a single point failure with 1 LED going bad.
Alan