DMG classifications get a bit complicated at times. The first step is also to find the major printing.
There are often variations within these, but always start here first. Leaving off the distinctions for the earlier non-revised printings, and the later printings, for brevity:
Non-revised printing = 5th or earlier
Wizard logo + "Revised Printing" + yellow flyleafs = 6th
Wizard logo + "Revised Printing" + white flyleafs + perforated ref sheets = 7th.
Wizard logo + "Revised Printing" + white flyleafs + unperforated ref sheets = 8th.
Face logo = 9th or later.
Find out where you are there. It seems like you have 7th or 8th printing, but you haven't spoken about perforations or logos, so I can't be sure. It might be a 9th or later.
In any event, I don't think it's a printing variant, but a binding error. With regards to the pages, it looks like during the binding process the third signature (pages 33-48) was accidentally replaced with a fourth (pages 49-64). Then the book was bound as normal, including an additional fourth. Not uncommon with printing these books, but a curiosity.