Patrick DERWAEL:
--> cloned VM, changed IP and mac adresses, OS hostname, Tor nickname and restarted the Tor service
Surprise: the fingerprint of the clone is identical to the one of the source VM
There is no surprise. You've probably just cloned DataDirectory which contains long-term relay private key and edited only torrc (nickname, ports, whatever). Try to clear DataDirectory out and restart tor - it should regenerate the keys.
-- Ivan Markin