Customer subdomain put on wrong site?

[Norman]

I have a customer who has created site

subdomain.domain.ext
it also has the following co-domains:
www.subdomain.domain.ext
and subdomain.domain.ext

Since upgrading to the latest ispconfig 2 version we've seen some sporadic weird behaviour.
One was /etc/passwd being nulled and now this new problem.

It seems that subdomain.domain.ext was also put on entirely different sites co-domain list belonging to a totally different customer under another reseller.

What may be the cause of this?

the subdomain can't be edited as admin, it simply says I dont have permission to access this object.

co-domain subdomain.domain.ext on the site 1 and site 2 has different docids.

What would be a quick fix?
and what would be a permanent fix to make sure this wont happen in the future?

Is there any known issues such as this with doublette co-domains?