code: function isAlreadyReplicating(state, feed_id, ignore_id) {
    for(var id in state.peers) {
      if(id !== ignore_id) {
        var peer = state.peers[id]
        if(peer.notes && getReceive(peer.notes[id])) return id
        if(peer.replicating && peer.replicating[feed_id] && peer.replicating[feed_id].rx) return id
      }
    }
    return false
  }
docs: check if a feed is already being replicated on another peer from ignore_id