Do not explain to me what processing time means, i know the answer already, and keep the oranges and apples for yourself.
You said the following :
Which means that they at the local visa office are going to put person (B) documents (which were received first) on hold and not starting processing it until they get person (A) documents (which were received after person B) or maybe are not received yet.
and that is completely wrong if you have an official source of your claim, provide it, if not, do not give me what you think.
You might wanna read this:
VII. Procedural notes
Lock-in date
The lock-in date will be the date that the application is received at the CIO (occupations on the list) or at the visa office (AEOs, Temporary Foreign Workers and International Students).
Source http://www.cic.gc.ca/english/resources/manuals/bulletins/2008/ob089.asp