Early PGI-produced Yaks are identical to the Chipco ones. Later ones (post-September 2013) are thicker. The early ones are 3.29mm on average, and the later ones are 3.38mm on average. I know this because I have custom Yaks from both time periods. I believe the blanks changed slightly in that time period.
Edit: Just reviewed my emails (it's been a while...), and I was told that it's possible that some older blanks were inadvertantly used. I didn't pursue it further since the chips are usable in stacks of 10. If I ever sell them, I'll advise the purchaser. But I have no plans on selling them anytime soon.
Here's stacks of 25. Stacks of 10 are close enough that I'm fine with them.
View attachment 22607
From Left to right...
Pink 25c (From July 2013)
Yellow 5c (From November 2013)
Blue $1 (From September 2013)
Red $5 (Chipco made)
In any event, the PGI "Chipco" blanks now in use for the PCF and Deja Vu chips seem more "rounded" on the edge than any of my Yaks.