Fascinating and very well spotted!
We can add a little more flesh about the registered addresses involved. Both house, but not exclusively, formation agents that provide Corporate Secretarial services to a very substantial number of companies.
The issue you have raised here has common ground with your post The need for better identifiers - discuss! and also my series (probably not yet concluded) about POTENTIALLY FICTICIOUS ADDRESS and / or PERSON(S).
There is, in our view, clear evidence of malicious intent in each example exposed and of the need for a policing effort to minimise the scope for harm. I am sure that this is outside the Companies House remit but when suspicions are raised by designated bulk users perhaps the CH Integrity Team could review / accept the suspicion rationale and then error names so these revert to number and error addresses to the appropriate CH default address until such time as the suspicion is removed or default compliance procedures result in dissolution.
Could this be a plan to stamp on clear malicious intent?
Can it be improved on?
Can and will CH implement it within their existing powers and resources?
Discussion would be welcomed and improvements / CH prompt action welcomed.
(firstname.lastname@example.org for those who want to keep discussion out of the public domain.)