As defined in the first part of this article, pair isograms are words containing exactly two of each letter. Those 7 pair isograms in the following lists which exhibit an accidental first-half/last-half symmetry or balance are asterisked for the reader's convenience.
Borgmann, Dmitri A.
"Long Isograms (part 2),"
Word Ways: Vol. 18
, Article 5.
Available at: http://digitalcommons.butler.edu/wordways/vol18/iss3/5