First of all, your question is really about your home network which is explicitly off-topic here.
Additionally, despite the fact you could find such a setup in office building, this is in violation of the cabling standard.
I.E. it is not a professional way of cabling and many issue - really difficult to diagnose - can arise due to this non-compliant setup.
This site is about professional networks maintained according to industry good practices. Such hacks fall out the scope of the site.
I'm sure many people will be happy to answer this question on SuperUser.
