Leafletで同じ緯度経度の場所に違う情報のピンを立てたい場合

leaflet本サイトのサンプルをみて地図を作っているのですが、例えば、下記のように、ピンを立てる位置の緯度経度が完全に一致している場合で、情報を４つ同じ位置から表示したい場合はどうしたらいいのでしょうか？

ピンをクリックした時に４つとも（下記で言うと、This is Littleton,This is Littleton02,This is Littleton03,This is Littleton04,）の情報を確認出来るようにしたいです。

L.marker([39.61, -105.02]).bindPopup('This is Littleton, CO.').addTo(cities),
L.marker([39.61, -105.02]).bindPopup('This is Littleton02, CO.').addTo(cities),
L.marker([39.61, -105.02]).bindPopup('This is Littleton03, CO.').addTo(cities),
L.marker([39.61, -105.02]).bindPopup('This is Littleton04, CO.').addTo(cities);

Javascript
1
2
3<!DOCTYPE html>
4<html>
5<head>
6	
7	<title>Layers Control Tutorial - Leaflet</title>
8
9	<meta charset="utf-8" />
10	<meta name="viewport" content="width=device-width, initial-scale=1.0">
11	
12	<link rel="shortcut icon" type="image/x-icon" href="docs/images/favicon.ico" />
13
14	<link rel="stylesheet" href="https://unpkg.com/leaflet@1.0.1/dist/leaflet.css" />
15	<script src="https://unpkg.com/leaflet@1.0.1/dist/leaflet.js"></script>
16
17
18	<style>
19		#map {
20			width: 600px;
21			height: 400px;
22		}
23	</style>
24
25	
26</head>
27<body>
28
29<div id='map'></div>
30
31<script>
32	var cities = new L.LayerGroup();
33
34	L.marker([39.61, -105.02]).bindPopup('This is Littleton, CO.').addTo(cities),
35	L.marker([39.61, -105.02]).bindPopup('This is Littleton02, CO.').addTo(cities),
36	L.marker([39.61, -105.02]).bindPopup('This is Littleton03, CO.').addTo(cities),
37	L.marker([39.61, -105.02]).bindPopup('This is Littleton04, CO.').addTo(cities);
38
39
40	var mbAttr = 'Map data &copy; <a href="http://openstreetmap.org">OpenStreetMap</a> contributors, ' +
41			'<a href="http://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, ' +
42			'Imagery © <a href="http://mapbox.com">Mapbox</a>',
43		mbUrl = 'https://api.tiles.mapbox.com/v4/{id}/{z}/{x}/{y}.png?access_token=pk.eyJ1IjoibWFwYm94IiwiYSI6ImNpandmbXliNDBjZWd2M2x6bDk3c2ZtOTkifQ._QA7i5Mpkd_m30IGElHziw';
44
45	var grayscale   = L.tileLayer(mbUrl, {id: 'mapbox.light', attribution: mbAttr}),
46		streets  = L.tileLayer(mbUrl, {id: 'mapbox.streets',   attribution: mbAttr});
47
48	var map = L.map('map', {
49		center: [39.73, -104.99],
50		zoom: 10,
51		layers: [grayscale, cities]
52	});
53
54	var baseLayers = {
55		"Grayscale": grayscale,
56		"Streets": streets
57	};
58
59	var overlays = {
60		"Cities": cities
61	};
62
63	L.control.layers(baseLayers, overlays).addTo(map);
64</script>
65
66
67
68</body>
69</html>
70