Sorry for confusion :) I've thought somebody is posting kind of spam messages in Checker. Nice it's not true.
I understand now what you are about - adding an extra function to Checker which doesn't keep Pre-moderated posts, right?
I think there may be some difficulty. I see the possibility of how Checker would skip all of such messages, before saving them to cache. But as soon the message goes live, the Checker will interpret it different way, and will still show in a queue "after" it was accepted from pre-moderation.
Also, considering Pre-moderation add-on may be used by multiple members, meaning you have entered it and see some messages doesn't mean they are all of the new messages since your last appearance. Some messages in a topic also can not be in Pre-moderation queue, but they can be in your Checker. Checker just allows to review the topic in whole.
So I think, you must some way live with it - if you have both add-ons installed, then
- first enter and review all Pre-moderated messages,
- then enter and review the Checker (all topics and messages in whole with possibly new messages from the non-premoderated members).
That should avoid the confusion of this effect - obviously, you should not enter the Checker first ahead of Pre-moderation. Quite a native habit to work on, I think.