Hmmm, the remote doesn't seem to follow the rc5 protocol too well - or there's some bug in the IR receiver driver of your card that then causes rc-5 decoding in the kernel to fail.
On quickly repeated button presses you should see the toggle bit flipping instead of getting different scancodes for the same button. eg
799.923295: lirc protocol(rc5): scancode = 0x1015 toggle=1
800.183294: lirc protocol(rc5): scancode = 0x1015
But that's no big deal, you can work around it with 2 scancodes for the same button in your keytable - like you already did.
The more problematic thing is that the signals seem to arrive at about 250ms interval instead of 110ms which is the standard for the rc-5 protocol. Therefore the kernel will interpret the scancode as distinct button presses and the normal repeat handling won't work.
You should be able to work around this by increasing the IR receive timeout with eg ir-ctl -t 200000 - you can play a bit with the value, 150000 should probably work as well and give a bit better response or you can go up a bit, eg to 250000. Just test what works best for you.
so long,
Hias