Hi Andy,
thank you a lot for the information!
yes, it is the case where somebody Liked the link in the Facebook newsfeed.
I tried the query which you gave me, and it showed exactly 1 person, the person who Liked it in Facebook, but on my website it is still 0 likes. Do you know how to check whether the URL on my website is different than the Liked URL in Facebook?
Greetings,
Nikolay