All but the 1972 edition have Institute for Nouthetic Studies as their publisher; however, I've read that INS merged with MABTS and also acquired copyrights from Timeless Texts. The 2 titles that Logos has listed explicitly under MABTS aren't duplicated (yet).
Caveat: I've put the page counts in quotes, having learned from other Logos purchases that those are rough estimates.
The Importance of Faith in Counseling
The Time of the End: Daniel's Prophecy Reclaimed
Even with 2 Research Editions, how could I know which one will be tagged better, and how?
The Big Umbrella
The "vol. 1" added to the title of the latter makes it sound like it is only part of the whole, but the "Contents" lists on the product pages vary only by punctuation.
One disadvantage (verified by last week's completed Pre-Pub): only one of each pair will earn a dynamic discount.