Одновременное скрытие и отображение модального окна bootstrap 4 скроет полосу прокрутки браузера

.modal
{
  overflow:scroll !important;
}

<script src = "https://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script>
<link href = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel = "stylesheet" />
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<button type = "button" class = "btn btn-info btn-lg" data-toggle = "modal" data-target = "#myModal">Open Modal</button>
<div class = "modal fade" id = "myModal" role = "dialog">
  <div class = "modal-dialog">

    <!-- Modal content-->
    <div class = "modal-content" style = "overflow:scroll;">
      <div class = "modal-header">
        <button type = "button" class = "close" data-dismiss = "modal">&times;</button>
        <h4 class = "modal-title">Modal Header</h4>
      </div>
      <div class = "modal-body">
        <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
          It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with
          desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
        <br><br>
        <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
          It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with
          desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
        <br><br>
        <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
          It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with
          desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
        <br><br>
        <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
          It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with
          desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
        <br><br>
        <button type = "button" class = "btn btn-info btn-lg" data-toggle = "modal" data-target = "#myModal2">Open Modal</button>
      </div>
      <div class = "modal-footer">
        <button type = "button" class = "btn btn-default" data-dismiss = "modal">Close</button>
      </div>
    </div>

  </div>
</div>
<div class = "modal fade" id = "myModal2" role = "dialog">
  <div class = "modal-dialog">

    <!-- Modal content-->
    <div class = "modal-content">
      <div class = "modal-header">
        <button type = "button" class = "close2 close" data-dismiss = "modal">&times;</button>
        <h4 class = "modal-title">Modal Header</h4>
      </div>
      <div class = "modal-body">
        <p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book.
          It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with
          desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.</p>
        <br><br>
      </div>
      <div class = "modal-footer">
        <button type = "button" class = "close2 btn btn-default" data-dismiss = "modal">Close</button>
      </div>
    </div>

  </div>
</div>