That's right, you didn't say that. You said there is a "public" and a "private" list. To me this sounds like the "private" one is somehow hidden from the public and cannot be seen which isn't the case.
No, there is no private list, it's just the public one. You can check out the key header whitelist here: http://cheme.com/ Visit this site with "Acceptable Ads" enabled and disabled and you will see the difference. Notice the "data-adblockkey" in the source. This was publically announced in their "Acceptable Ads proposal" forum here and later added to the public list: https://adblockplus.org/forum/viewtopic.php?f=12&t=17699