As of now, Snapchat doesn't provide a direct way to see if someone has rewatched your Snap story. There's no official feature that gives you a list of who has rewatched it. So, in short, no, you can't really tell.
Snapchat doesn't provide a feature to know if someone rewatches your story. It's mainly concerned with showing the overall view count for your story. So, whether a person has watched it once or multiple times, you can't really tell. This is part of Snapchat's design to keep the user experience simple and focused on sharing content rather than detailed analytics of who rewatches what.
On Instagram, currently, you can't directly see if someone has rewatched your story. Instagram doesn't provide such a specific feature that shows exactly which users have rewatched your story. It mainly focuses on showing the number of views, but not the details of who rewatched it.
You might notice if they comment or message you about it again. Sometimes, they could also mention specific details that show they've watched it more than once.