Comment # 2 on bug 1099772 from Michal Srb

So libinput knows quirk "BOUNCING_KEYS" which disables debouncing.
Unfortunately it is not available in libinput 1.10.5 in Leap 15.

As a workaround on Leap 15 you can switch back to evdev. Easiest way would be
to remove /etc/X11/xorg.conf.d/40-libinput.conf. Or you can make a specific
rule, it would be something like this:

    Section "InputClass"
        Identifier "Contour Design RollerMouse"

        MatchProduct "Put the exact name here"
        # Or use some other Match* directives

        Driver "evdev"
    EndSection

We should also add the quirk to libinput database upstream, so it will work in
future versions.

Can you please post the exact "Input device name" from the output of evtest?