When using the bootstrap "checkbox". If they are duplicated to have more than one. When you click one, the two are clicked. Why? It seems that some javascript code activates them using their id or name, or something like that? How should you do to use several check boxes with bootstrap and each of them work independently?
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container mt-3">
<form action="/action_page.php">
<div class="custom-control custom-checkbox mb-3">
<input type="checkbox" class="custom-control-input" id="customCheck" name="example1">
<label class="custom-control-label" for="customCheck">Custom checkbox</label>
<br>
<input type="checkbox" class="custom-control-input" id="customCheck" name="example1">
<label class="custom-control-label" for="customCheck">Custom checkbox</label>
</div>
<button type="submit" class="btn btn-primary">Submit</button>
</form>
</div>
</body>
</html>