Variety in Queen's Portrait in $20 Polymer Notes?

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I was reading a Globe and Mail article regarding issues with the $20 polymer note and the vending machine industry in Canada.   There was one interesting paragraph that I found interesting, and perhaps could lead to a variety in the $20 Polymer notes. 

It's the following paragraph:
"Mr. Kabir said some manufacturers were caught off guard when the Bank of Canada issued slightly different versions of the new $20 bank notes. The entire image is offset in one version – the Queen’s chin is marginally higher, for example, which can foil automatic scanners programmed to expect the non-offset version."

Here is the link to the Globe's article:
http://www.theglobeandmail.com/report-on-business/economy/currencies/new-polymer-20s-spark-vending-machine-headaches/article6973809/

Thank you for sharing the link. I am particularly intrigued by the statement from the bank spokesperson that says:

“In the case of bank notes, it is completely normal for various bank note production runs to have subtle, virtually imperceptible variations in some characteristics, within a very narrow tolerance range.”

-Beeby, Dean, "New polymer $20s spark vending machine headaches", The Globe and Mail, Jan. 6, 2013.

Does that mean  that if the variations are really perceptible then they would be considered out of the normal? Also there is mention of "narrow tolerance range". I am wondering if the Bank provides additional details about the design of bank notes to the different stakeholders in the industry?

By the way who makes the calls regarding whether something is a variety or not. Is the Charlton GPM Catalogue the defacto standard authority in this realm? I noticed they do mention work done in this forum and also by the CPMS.