Wikimedia Bugzilla is closed!

Currently, if the user hard refreshes the page or opens another view of the same revision (say, diff view when you were previously on History), you can thank the same user twice for the same revision. 

This is potentially very confusing, since it appears like your previous thank you did not take effect. We should do our best to disallow this. 

I understand that, in order to keep this feature lightweight, we're not creating database tables etc. to keep a log of thanks. And that's probably good since it could easily grow right along with revision tables once enabled. 

As an interim solution, I'd support even a half-measure like preventing duplicate thanks for 24 hours at least, such as by remembering the thank yous for the duration of your session (tied to the session cookie, maybe using memcached, etc.).