No,
there is no conflict between aerofly FS and aerofly FS2.
I suppose you didn't fly aerofly FS for a while.
The reason is windows update. This changed the parameters for the registration key of aerofly FS.
Fortunately this is different with aerofly FS 2.
Please ask for a new registration key, try info@ikarus.net or search for a direct support mail address.