n. A book cover that closely resembles another.
Also Seen As
Some authors, who either use templates, free tools or bad designers are unaware that their book covers are book-alikes until readers point it out on Goodreads (check out their Same Cover Different Book list here — there are loads of these lists) or other sites.
—Leila Dewji, “Don't Be A Book-Alike,” Writers & Artists, June 08, 2015
We can therefore extend the benefit of the doubt to all the Shanghai girls, babies, dolls, etc. out there for their bookalikes, and even for their catty copycatting, though one hopes that, for the sake of the genre, China's banal book title formula of [CITY NAME] + [GENDER-SPECIFIC SOBRIQUET] will soon fall out of fashion.
—Tom Carter, “Shanghai Girls Gone Copy-Catty,” The Huffington Post, May 01, 2013
I’ve been keeping an eye out for cover trends. However, in addition to trends, I’ve also come across what I’ve termed “bookalikes”: book covers that are pretty much twins (some fairly identical, and some a bit more fraternal in looks, but you can be the judge of that.)
—Stephanie Campisi, “Bookalikes: cover twins and book covers with strong family resemblances,” Read in a Single Sitting, October 31, 2012
2006 (earliest)
Number 3: a cross-media bookalike as revealed by today's Observer.
—John Self, “Bookalikes” (reply), Palimpsest, April 23, 2006
Bookalikes. Source: Writers & Artists

An earlier usage (from August 15, 2000) of the term book-alike appears here, although in this case the writer is referring (I think, it's not entirely clear) to an object that looks like a book. So it's similar to the blook, a blend of book and look that's just unsightly enough to qualify as an early candidate for 2016's Cruft of the Year.