Within the demo page, you will find multiple carousels being utilized. The process of defining each carousel with a unique id is essential, as stated in the documentation:
"Be sure to set a unique id on the .carousel for optional controls, especially if you’re using multiple carousels on a single page."
For more information, visit the official Bootstrap documentation
<div id="thisShouldBeUniquePerCarousel" class="carousel slide" data-ride="carousel">
<div class="carousel-inner" role="listbox">
<div class="carousel-item active">
<img class="d-block img-fluid" src="..." alt="First slide">
</div>
<div class="carousel-item">
<img class="d-block img-fluid" src="..." alt="Second slide">
</div>
<div class="carousel-item">
<img class="d-block img-fluid" src="..." alt="Third slide">
</div>
</div>
<a class="carousel-control-prev" href="#carouselExampleControls" role="button" data-slide="prev">
<span class="carousel-control-prev-icon" aria-hidden="true"></span>
<span class="sr-only">Previous</span>
</a>
<a class="carousel-control-next" href="#carouselExampleControls" role="button" data-slide="next">
<span class="carousel-control-next-icon" aria-hidden="true"></span>
<span class="sr-only">Next</span>
</a>
</div>