No. The WP featured image can only have one image assigned to it.
This is a WP question, not really an ACF question. You would need to filter WP functions that get and show the post thumbnail. For example this function that gets the thumbnail ID is filterable https://developer.wordpress.org/reference/functions/get_post_thumbnail_id/.
I could potentially give you code to alter this but I have no idea what else would need to be modified.
