I duplicate my modal button and The problem is I can't show "Open Modal 2" in my code.
<button id="myBtn">Open Modal</button>
<div id="myModal" class="modal">
<p>Some text in the Modal..</p>
You should use different ID for your "Open Modal 2" elements.
According to definition and usage from W3School,
the getElementById() method accesses the first element with the specified id.