HDMI Cec is kinda clunky. One of those cures for a problem that doesn't really exist.....

You can always just cover up the ir eye on the bluray player you don't want to control when you aren't using it. Not really ideal I know. smile I think on some denons the hdmi Cec can be set individually per input/output. You may have to set it per the hdmi port the urc bluray is hooked up to and globally in the general settings.

I've only messed with one recently and I disabled it everywhere I could.