OSMC supports multiple remotes and multiple receivers being active at once, whether lirc based, USB etc, and the event streams of each receiver are mixed together by eventlircd before being sent to Kodi. So if you have two different receivers that are both configured to receive the exact same remote you will get repeats, and you may actually get stuck down repeats as well.
So don’t do that. 
Only one receiver should be configured for any given remote.
That is correct - USB connected remotes do not go through lircd therefore you will not see output from them at /var/run/lirc/lircd-lirc0. Only remotes being received and decoded by lircd will show output at this socket.
A USB remote may show output at /var/run/lirc/lircd which is the output of eventlircd. This will happen if eventlircd has been configured to handle this type of USB receiver. (This is done in udev rules)
If there are no udev rules that match the USB receiver then Kodi will directly receive the uinput events from the device and bypass eventlircd altogether, in this case you won’t see any output at /var/run/lirc/lircd. One such example would be a regular keyboard.