Each npm linked package has its own set of node_modules, therefore there might be multiple copies of react-broadcasts required by an app (all with the same version). Each of them ofc maintains its own uid counter but broadcasts is a shared key on legacy context and all those copies override what the put in context.
Don't have better idea on how to deal with it than randomizing broadcasts key (at least in development), thoughts? Can prepare a PR handling this if you find it worthwhile.