This has been a bug going forever;
Most people aren’t even aware that they repost.
I’ve experienced this for ages now.
Pretty sure that form resubmission upon refresh is a standard across websites? It’s not really a web bug but a user error; the browser is sending a message to Roblox saying “hey, I’ve got this data in a POST request for you” and Roblox has no (built-in) way to determine that was caused by a refresh other than deliberately submitting the form.
It also happens when you’re exiling a user and confirm the pop-up dialog.