The problem is that you're rendering two carousel items for each image, one of which is marked as "active". Looking at
the documentation[
^], only the first item should be marked as "active".
Try changing your loop to:
int x = 0;
string cssClass = "item active";
foreach (var img in Model.POIsImages)
{
@Html.Hidden("imageids[" + x + "]", img.ImageId);
<div class="@cssClass">
...
</div>
cssClass = "item";
x++;
}