First, are you aware of the very recent "root user" security issue with High Sierra? I had actually posted a thread about that last week:
Also, the "way" Apple kind of "botched" it up:
Now, the Combo Updater is good because it provides ALL the OS updates that Apple has released for a particular OS. IN this case, it would include the "fixes" in V10.13.1, plus that "root user" security fix, and some "new" ones in OS 10.13.2 itself. Don't worry, it will not completely overwrite your OS 10.13.1 "stuff".
By the way, how are your experiences with High Sierra? A number of folks have been reporting various issues with High Sierra. I even started a thread, asking folks to post their experiences with High Sierra. So far, only 1 person has responded:
Myself, I am still waiting for the High Sierra upgrade for Tech Tool Pro (all my other third party software is either already compatible, or updates have been released). But even if that upgrade was available, I am still somewhat reluctant to upgrade. That's why it would be good if folks would posts their detailed experiences with High Sierra.