What is different for the members who didn't lose their post count and those of us who did (twice)?
If I understand what you're asking, the difference is in how long you have been a member. Because we lost every registration and post since 28 Aug. 2012, counts were reset to what they were on that date. Anyone who registered after that date had to recreate their account and start again from a post count of zero. Others who had been members longer lost perhaps thousands of posts but still retained those posts they had made before that date.
I myself lost somewhere in the neighborhood of 6,000 posts in the two resets.