Something struck my eye today that I have never noticed in the 29 years I’ve owned this book.
Starting on page 6, there is a section labeled “Special Entries” which has the following introduction:
“Certain creatures, such as devas, have special abilities or live in unusual places, etc., and these may require the notations explained below.”
What follows are explanations for monster stats such as “Plane”, “Intelligence as it affects spells”, “Constitution”, and several others, which look like they were originally intended to be listed in at least some monster listings as standard stats, but it appears as if the idea was dropped and the excision never made to the “How to Use this Book” section at the front. Only the stat on “psionic ability” seems to have been used at all. Even the entry on devas doesn’t have a listing for “Plane”.
I know things were a bit hectic in 1982/1983 at TSR, but this is an entire page of material that seems to have been included as an oversight. Yikes!
While it's similar, rainswept, it's not quite the same. There are some things mentioned in Deities & Demigods that aren't included in the MM2 intro, and there are some things in MM2, such as "Intelligence as it pertains to spells" that don't appear in D&Dg.
Tempting as it might be to dismiss it as what we would today call a copy and paste error, there's stuff in MM2 that was unique to it, which makes the whole thing all the weirder.
If you want to see a mess, take a look at the monster listings by terrain type at the back of that book. They must have typed it up the night of the TSR Christmas party or something.