You can upvote question on answerhub multiple times

This works only on other people question. If You click on upvote button very fast twice it will add 2 upvotes most of the times. If You click then twice fast You can remove 2 points to original amount. Real problem starts when You click once to remove point and then refresh page. Now You can add points again, so by adding 2 points and removing 1 You can probably add infinite amount of points to some post.
Upvote persist when opened in another browser or computer.

You can also use this to superdownvote someone post.
I found out and tested using this question (How can i spawn actors based on an image mask? - Blueprint - Unreal Engine Forums) There are 5 upvotes, all by me. (I came to higher values).

Those extra upvotes doesn’t seem to add up to user score, as SarahLee1 score did not increase more than up to 6 points.

you should probably look again, theres actually only one upvote one that question.

@dzarafata: Are you sure it’s no a purely visual glitch? I’ve seen this happen when using a broken, double clicking mouse.

And yeah, as ThompsonN13 said, I can see 1 up on this question only. Hit shift+F5 to reload page (discards cache). See if it changes.

I checked with incognito mode which should behave like discarding cache. Also I see only one upvote now. I did it again and checked with my smartphone. I now see 2 upvotes/ My guess is that’s related to website caching on server. Doesn’t seem to be a big deal if it’s going back to normal after some time