Clicking a second time transmits your recommendation. If you are already logged into a social network of your choice, this occurs without an additional window. Because this is a direct transmission, we do not receive any information on the transmitted data. The information transmitted states that you have opened the corresponding page. If you are simultaneously logged into Facebook & co. this information will be delivered to your social media account and therefore linked to you.
To find out more about the use and storage of your personal data by Facebook, Google+ and Twitter, please contact these social media companies directly. You can also block the social plug-ins with browser add-ins.