Hi!
Looks like there is an ‘invisible’ duplicate of the same search shortcode on the page. It is a very rare issue, usually happens on mobile menus, that use a ‘duplication hack’ to create a mobile/tablet version of the menu contents. I can’t tell for sure only from a screenshot though.
Try turning on this option on the back-end: https://i.imgur.com/6b4kpne.png
It should resolve the issue, if the duplication happens before the page load is complete.