@Georg: a restart indeed seems to “solve” the issue temporarily, but the problem comes back rather soon. Using the front or back of the remote does not make a difference.
As i wrote, this is another indicator for me it might be an buffer overflow or memory related issue, so i was about to delete some large apps……but before doing that, i checked the Apps that are activated under Accessibility, since those can be active “in between” the remote and the user interface.
On my tv, Projectivy Launcher is installed, and was activated under Accessibility apps, I deactivated this, did NO reboot yet, and now the double click problem really seems to be solved! The remote is much smoother than before, and even with some long press and hold navigation, no double or triple clicks anymore.
Reset the log buffer size to the original value (256 kB) and it still keeps working ok now.
Have to wait and see if this keeps working, and of course will do the same on the ohter two TVs, to be sure this deactivating Accessibility is indeed the solution, but this seems very promising.
Others with this problem can try the same to see if deactivating Accessibility for some or all apps, works for them too.