I have a “hotel circuit” ( I do not know the english word) currently with a single switch connected to a Fibaro double switch. This works fine.
I want to replace the single switch with a double so I can use the second switch of the Fibaro with an automatization. Can some help me how to connect the wires? See the image.
Many thanks!
The installation manual 
found on the offical site 
https://manuals.fibaro.com/switch-2/#cat-158 tells us 
Notes for the diagrams:
S1 – terminal for 1st switch (has the function of activating the learning mode)
S2 – terminal for 2nd switch
L – terminal for live lead
Q/Q1 – output terminal of the 1st channel
Q2 – output terminal of the 2nd channel (only Double Switch 2)
N – terminal for neutral lea
B – service button (used to add/remove the device and navigate the menu)
So all you need is to wire your second load between Q2 (L) and (N). 
For a double switch you have the dedicated terminals S1 and S2 to detect switching. 
Can’t get much easier actual but in case that’s already to complicated better get someone professional to do the wiring for you 
Thanks! The part of the Fibaro is clear to me. It concerns the wiring in of the switch in the wall box. See the image , these wires are not connected.
Well, I would just get rid of this “hotel circuit” device as it looks like to do nothing? So the two wires coming from the (double) wall switch will go directly to the S1/S2 terminal of your fibaro 
This was the original setup. lamp was replaced by the Fibaro.
The second single wall switch needs to be replaced by a double.
The second switch needs to activate a automatization with the fibaro
That information would have been more than useful in your very first post! Please try to give all Information upfront when you seeking for help like described here
And check the link posted by aceindy as it hosts the possible configurations for your scenario 
