fallbackswitch plugin support for interpipe

[minusplusminus]

Hi,

Currently i'm using interpipe on a Jetson Nano with tegra r32.7.3. I've installed both the rust fallbackswitch plugin and want to combine the plugin with interpipe. combining these results in interpipe logging a warning
Could not send event upstream, more than one listener is connected

which sounds logical because interpipe sends events to listener but fallbackswitch creates two. Second one is based on fallback-uri

I propose that it would be nice to add an option to send to a specific listener if this is the case. Did I miss this in the docs? Or is this a nice bugfix/enchancement?