My opinion:
OINP employees should reveal their dealers (they must have some high quality stuff there)

;D
But now seriously.
The wording there is a bit unclear.
After you successfully register a profile, you must submit your application to the OINP within 14 calendar days.
Any NOIs sent as of February 23, 2017 will be valid for six months for applications to the HCP stream.
Take it as my personal opinion.
Most obvious explanation:
You have 6 months to answer NOI and send your application. But once you start One key account and get your case number, you must submit within 14 days.
What is not clear is, if you will be able to register another One Key account on the same NOI after you let the other one expire (or even before the first one expires). Somebody who have already submitted might want to test that part). And if that is technically possible (the software does allow it), will they check their system for all old expired One Key registrations and compare it with your current application?
[SS]: Vague statements do creates chaos. Wat could be more evident example then this ;D . Though your One Key registration part do make sense and yes it will require an attempt to do test the same. However even though as logical this might sound, one needs to be sure of, as its a matter of loosing NOI (if they meant wat they have written). I have drop in a mail to OINP and awaiting response, waiting to call as well at the right time. Hoping that a similar clarification will be provided by them.
Alternative meaning can be:
You have 14 days to submit from NOI and no new NOI will be issued to you next 6 months if you miss this opportunity.
I know that part is hardly visible. But they do check possible applicants in person (somebody confirms who shall get NOI). So what if that person will also check and compare older NOI in order not to issue 2 NOI to the same person (just because he or she has deactivated an old profile and activated a new one).
[SS]: In this case wat could be the intent of talking about 6 months validity (6 months ban doesn't sound logical as they opens nearly for 2-3 months). Also i believe through online channel its a cakewalk to filter out the profiles (via EE numbers, email-ids etc) for repeated invitations. Since for the cases which misses 14 day deadline, can still apply with everything new (like u already accounted and stated below).
If they have this 2 stage timing, they shall exactly explain all options (with creating new EE account, creating new One Key account with new case number).
Like this it is still ambiguous.