Why does the same title sometimes appear
in both giant and regular bindings?

Nobody has come up with a good answer for this one.

Usually Modern Library used the giant editions to create longer collections (Faulkner Reader) or general anthologies (Great Tales of Terror and the Supernatural), or when the book block was too big for the regular editions (Tolstoy's War and Peace). Typically these editions were over 1,000 pages.

But sometimes the same titles were available simultaneously in both regular and giant bindings:

Tolstoy's Anna Karenina
Dostoyevsky's Brothers Karamazov
Cervantes' Don Quixote
Melville's Moby Dick
Fielding's Tom Jones

Sometimes the prefaces or translations in the giants were different from those in the regular editions, but not so different that the page count increased substantially. In the case of the Cervantes (1964-1970, Putnam translation) the giant edition used bigger type—a good reason to use a bigger binding.

Speculation has it that these extremely popular titles were often used as college texts—the two sizes were available to satisfy the varying demands of instructors, some of whom liked the larger size while others liked the more classic format.

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