Eddy C wrote an answer about POC Octal Helmet on March 24, 2014
I think you are correct. The weights shown on the POC site list both European versions (CE standard) and those that are US versions (CPSC standard) in terms of safety standards. From my understanding all helmets shipped to the US must meet CPSC standards. This version, from what I have found, required additional materials to meet the standard hence the heavier weight(s).
This blog had an interesting write up on it:
As for the weight that is shown on the CC site for a Medium @ 192 grams - CC needs to change that. A medium helmet being shipped to the US under CSPC standards will weigh 250 grams per POC's website (http://www.pocsports.com/en/product/1879/octal).
Screen shot below from the site.