Bug in Amazon scams me into buying more units than I asked for

For the past few weeks, whenever I try to buy 1 of something on Amazon with the "buy now" button, an order for between 2 and 5 often ends up being created.

I figure if this is affecting me, there must be a large subgroup of users who are having orders stuffed for product they don't want.

I've tried to contact support, but no one cares / believes me.

Video of the bug in action:

https://www.youtube.com/watch?v=Nq53MlnqSnU