iMON PAD remote "doublecklicking"

I have a HTPC build in a SILVERSTONE SST-ML02B-MXR Milo case, which contains the iMON PAD ir receiver and remote (and a LCD display).

I was following this wiki article setting up the remote: Infrared Remotes [LibreELEC.wiki]

ir-keytable gives me this:

Found /sys/class/rc/rc0/ (/dev/input/event9) with:
        Name: iMON Remote (15c2:0038)
        Driver: imon, table: rc-imon-pad
        lirc device: /dev/lirc0
        Supported protocols: rc-6 imon
        Enabled protocols: imon
        bus: 3, vendor/product: 15c2:0038, version: 0x0003
        Repeat delay = 500 ms, repeat period = 125 ms

As I want to use a universal remote, which I also use for the rest of my equipment, I successfully switched the protocol to rc-6 and all keys are working (even the Power key) but I get doublecklicks on some keys, for instance Mute, Play, Pause, other keys are working fine (for instance Up, Down, Left Right).

I thought something is wrong with my universal remote, so I tried it with an original MCE remote and the problem is exactly the same.

By doublecklicks I mean, when I press for instance Mute, it gets Muted and instantly un Muted. The only way around is holding the key a little longer but it's hit or miss.

Log:

2020-06-06 14:15:46.704 T:140459145783424   DEBUG: HandleKey: launch_app1_pc_icon (0xc0) pressed, action is Mute
2020-06-06 14:15:47.914 T:140459145783424   DEBUG: HandleKey: launch_app1_pc_icon (0xc0) pressed, action is Mute

Is there a way to fix this?

I mean some repeat settings or so.

PS: FYI the Power key works in the rc-6 mode even for power on until I switch the PSU off, then only the iMON remote works for power on.