Can you get banned for clicking buy as many times as possible on an order for a card. Making it so you buy multiple cards at once rather than just one. After doing so you get all the orders, but the screen says the reCaptcha has experienced an error.
Captcha is maintaining a state in your browser that you are a real human. It verifies this by making you match images, which it is hard for AI to do still (not really, but...).
It would be a hassle to to do this every time, so ReCaptcha let's you keep making transactions as long as the state is maintained. Occasionally, it goes wrong and you get this error. But you are not breaking any rules by clicking more than once.