CT
You certainly are correct. especially if two circuits are involved and the neutrals are shared/paired, if somebody else comes along to troubleshoot and shuts off one of the curcuit that he thinks hes working on the neutral is still carrying return current and if he opens the neutral(which is suppose to be off) he s now in series with 120 volts.
This also violates 250.6, objectionable current, due to mis-wire. This alos creates a net current that shouldnt be there because all the neutrals are tied together, and a huge magnetic field. Whether there is any truth to the stray magnetic field is dangerous to the health of humans or not. This is bad practice.
WOC