Programming can never be perfect. Every code, no matter how well written, can always be worked around by other skilled people.
This is why TOS exists, to state what is not allowed, regardless if players are actually able to exploit it or not.
In regards of this instance, it is not allowed that same person plays more than one account simultaneously (logged in at same time). Regardless if this is done with software, or otherwise.
You can try to find "loopholes" in wording, but this will still not be allowed, and potentially questionable wording (if there is one) will get fixed and re written.