Hello,
(Kudos for phrasing the $subject :-)
A little exposure of internals: the processes that tag probes (based on results received from the probes) have various safeguards to avoid unfair tags and untags. Unfortunately in this case the "these two tags are mutually exclusive" was not used. In addition the wrong tag was not removed due to a different (otherwise generally useful) protection mechanism.
After realising this we convinced the system to apply the correct tags, and have ideas on how to avoid this happening in the future.
Thank you for bringing this up!
Regards,
Robert for the RIPE Atlas team