Interesting, Jörg ... I found a coffeepot described as Alquier's by a knowledgable dealer on the big online website. Like mine, it is struck twice with maker's mark only. The marks are more worn than on mine, they appear very close to mine although not exactly so if you look carefully.
Here they are together. Mine is on the left.
The style of mine still appears to me very different ... but yes, the marks are so similar ...
Thank you for your help. I hope Blakstone sees and comments.