understanding corebluetooth didDiscover peripheral

Hello,

I am trying to get my head around the CoreBluetooth framework. From different code samples I found here and there I managed to write a very simple script that scans for Bluethooth peripherals but I a m a bit puzzled by the result.

Why do I get duplicates in the list of peripherals ? (typically my iPad almost always appears twice)

Why do I sometime get a "nil" peripheral ?

<CBPeripheral: 0x1c011a040, identifier = A02449FF-A70C-92FC-1950-9DDFC0709126, name = Adafruit, state = disconnected>

what is 0x1c011a040 ?

Thanks !

//
//  ViewController.swift
//  BLE2
//
//  Created by UoC on 15/10/2018.
//  Copyright © 2018 Matt. All rights reserved.
//

import UIKit
import CoreBluetooth

let myCBUUID = CBUUID(string: "0x1c01135f0")

class ViewController: UIViewController {

    // Variables
    var myCentralManager: CBCentralManager!
    var myPeripherals =  Array<CBPeripheral>()
    
    // IBOutlets
    @IBOutlet weak var myTableView: UITableView!
    
    // Functions
    override func viewDidLoad() {
        super.viewDidLoad()
        myCentralManager = CBCentralManager(delegate: self, queue: nil)
        myTableView.dataSource = self
    }
}


// Class extensions
extension ViewController:UITableViewDataSource{
    
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return myPeripherals.count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let myCell = myTableView.dequeueReusableCell(withIdentifier: "myReusableIdentifier")!
        let myPeripheral = myPeripherals[indexPath.row]
        myCell.textLabel?.text = myPeripheral.name
        return myCell
    }
}

extension ViewController: CBCentralManagerDelegate{
    
    func centralManagerDidUpdateState(_ central: CBCentralManager) {
        if central.state == .poweredOn {
            print("powered on")
            myCentralManager.scanForPeripherals(withServices: nil, options: nil)  // withServices: nil or [myCBUUID]
        }
    }
    
    func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String: Any], rssi RSSI: NSNumber) {
        print(peripheral.name as Any)
        //print(RSSI)
        //print(UUID.self)
        //print(myPeripherals)
        myPeripherals.append(peripheral)
        myTableView.reloadData()
    }
}