I assume, that your test has been before the Tor browser 11 update? You can also look at the signature. If there is a signature you didn’t set, then someone else shares the same ID as you. If there is no signature present, you can insert one, so others can realize that too. Or you visit CreepJS every few days and look whether your ID has changed (so different fingerprint on revisit) or the visits counter increased more than one (others share the same fingerprint).