duplicate receive messages arriving?

[DrYSG]

This is very odd. I have a C++ program using nng Nanomsg (wire protocol is identical to nanomsg).
https://github.com/nanomsg/nng

I have a simple test harness (client.exe and server.exe) using the CPP interface and I only see one copy of a message (sent in over bus protocol). However with this JS package I am getting two copies of each message sent (cpp -> JS node program).

Node Version: 10.9.0
nanomsg: 4.0.2

This means that I get two calls to the receive() callback for each packet that arrives.

Here is my nanomsg receiver

const nano = require('nanomsg')
const { Topics } = require('./Payloads/Packet')

class LMB {
    constructor(config) {
        this.sock
        this.config = config
        this.nodeName = config.nodeName
        this.topicList = config.topicList
        this.topics = Topics
    }

    connect() {
        this.sock = nano.socket('bus')
        this.sock.bind(this.config.urlList[0])
        this.sock.connect(this.config.urlList[1])
        this.sock.on('data', this.receive.bind(this))
    }

    send(topic, payload) {
        let size = payload.length
        let packet = new ArrayBuffer(size + 8)
        let buffer = new Uint8Array(packet)
        let view = new DataView(packet)
        view.setUint32(0, topic, true)
        view.setUint32(4, size, true)
        buffer.set(payload, 8)
        this.sock.send(buffer)
    }

    receive(packet) {
        let view = new DataView(packet.buffer)
        let topic = view.getUint32(0, true)
        let size = view.getUint32(4, true)
        let payload = packet.slice(8, packet.length - 1)
        global.Dispatcher.process(topic, size, payload)
    }
}

module.exports = { LMB }

and here is the config that it uses, and the two copies of the start message that appear. I confirmed with the VSCODE debugger via breakpoints and the receive() method is being called twice for each arrival of a packet over the network.

C:\Program Files\nodejs\node.exe --inspect-brk=48723 orch.js 
Debugger listening on ws://127.0.0.1:48723/a3bc5322-9c99-4c22-b1fb-f053bb8d144f

For help, see: https://nodejs.org/en/docs/inspector

Orcestrator config: 
{
    "nodeName": "YSG4206-Orchestrator",
    "urlList": [
        "tcp://127.0.0.1:2019",
        "tcp://127.0.0.1:2018"
    ],
    "topicList": [
        "sim.Actor.State.Test"
    ]
}
Waiting for messages..
{
    "topic": 6,
    "size": 144,
    "topicString": "scenario.Ready",
    "source": "AFSIM-YSG-Server",
    "systemTime": {
        "low": -433850073,
        "high": 30695395
    },
    "systemTimeString": "Tue Oct  9 11:22:32 2018",
    "description": "AFSIM Ready"
}
******* starting ******
{
    "topic": 6,
    "size": 144,
    "topicString": "scenario.Ready",
    "source": "AFSIM-YSG-Server",
    "systemTime": {
        "low": -433850073,
        "high": 30695395
    },
    "systemTimeString": "Tue Oct  9 11:22:32 2018",
    "description": "AFSIM Ready"
}
******* starting ******

[DrYSG]

It was suggested that I should not be doing both a bind(local) and connect(remote) and that that might be causing two connections to be made. But I am finding that I need both for there to be traffic,.

currently:

local = tcp://127.0.0.1:2019
remote = tcp://127.0.0.1:2018