How to add multiple modal images using Bootstrap
<p>I currently have 2 images that I want the user to be able to click on and have it popup, but so far only one image is working. I know that both images have the same id, but when I try changing the id's I have to create new CSS code, etc.</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
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<pre class="snippet-code-js lang-js prettyprint-override"><code>// Get the modal
var modal = document.getElementById('myModal');

// Get the image and insert it inside the modal - use its "alt" text as a caption
var img = document.getElementById('myImg');
var modalImg = document.getElementById("img01");
var captionText = document.getElementById("caption");
img.onclick = function(){
    modal.style.display = "block";
    modalImg.src = this.src;
    modalImg.alt = this.alt;
    captionText.innerHTML = this.alt;
}

// Get the &lt;span&gt; element that closes the modal
var span = document.getElementsByClassName("close")[0];

// When the user clicks on &lt;span&gt; (x), close the modal
span.onclick = function() { 
  modal.style.display = "none";
}</code></pre>
<pre class="snippet-code-css lang-css prettyprint-override"><code>/* Style the Image Used to Trigger the Modal */
#myImg {
    border-radius: 5px;
    cursor: pointer;
    transition: 0.3s;
}

#myImg:hover {opacity: 0.7;}

/* The Modal (background) */
.modal {
    display: none; /* Hidden by default */
    position: fixed; /* Stay in place */
    z-index: 1; /* Sit on top */
    padding-top: 100px; /* Location of the box */
    left: 0;
    top: 0;
    width: 100%; /* Full width */
    height: 100%; /* Full height */
    overflow: auto; /* Enable scroll if needed */
    background-color: rgb(0,0,0); /* Fallback color */
    background-color: rgba(0,0,0,0.9); /* Black w/ opacity */
}

/* Modal Content (Image) */
.modal-content {
    margin: auto;
    display: block;
    width: 80%;
    max-width: 700px;
}

/* Caption of Modal Image (Image Text) - Same Width as the Image */
#caption {
    margin: auto;
    display: block;
    width: 80%;
    max-width: 700px;
    text-align: center;
    color: #ccc;
    padding: 10px 0;
    height: 150px;
}

/* Add Animation - Zoom in the Modal */
.modal-content, #caption { 
    -webkit-animation-name: zoom;
    -webkit-animation-duration: 0.6s;
    animation-name: zoom;
    animation-duration: 0.6s;
}

@-webkit-keyframes zoom {
    from {-webkit-transform:scale(0)} 
    to {-webkit-transform:scale(1)}
}

@keyframes zoom {
    from {transform:scale(0)} 
    to {transform:scale(1)}
}

/* The Close Button */
.close {
    position: absolute;
    top: 50px;
    right: 35px;
    color: #f1f1f1;
    font-size: 40px;
    font-weight: bold;
    transition: 0.3s;
}

.close:hover,
.close:focus {
    color: #bbb;
    text-decoration: none;
    cursor: pointer;
}

/* 100% Image Width on Smaller Screens */
@media only screen and (max-width: 700px){
    .modal-content {
        width: 100%;
    }
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!-- Trigger the Modal --&gt;
                &lt;img id="myImg" src="img/roof.jpg" alt=" Riga, Latvia" width="300" height="200"&gt;
                &lt;img id="myImg" src="img/personal.jpg" alt=" Riga, Latvia" width="300" height="200"&gt;
                &lt;!-- The Modal --&gt;
                &lt;div id="myModal" class="modal"&gt;
                
                &lt;!-- The Close Button --&gt;
                &lt;span class="close" onclick="document.getElementById('myModal').style.display='none'"&gt;&amp;times;&lt;/span&gt;

                &lt;!-- Modal Content (The Image) --&gt;
                    &lt;img class="modal-content" id="img01"&gt;

                &lt;!-- Modal Caption (Image Text) --&gt;
                &lt;div id="caption"&gt;&lt;/div&gt;
                &lt;/div&gt;</code></pre>
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