CommandD:
I've been an obsessive EC fan for over 15 years. Even my parents were too young for the originals (I was born in 1982), but I started following the reprints when I was a kid and own quite a large collection of EC stuff.
I don't know of any website, even wikipedia (I'm the one who wrote the wikipedia reprint history that was copies and pasted here), that has a complete checklist of the reprints. I can help you based on my own personal knowledge though.
To my knowledge, here are the EC reprints that exist (except for the new EC Archives that are just coming out, not familiar with their exact publishing history since I'm not collecting them, having already owned pretty much everything EC). To save time I'm not gonna state what each issue reprints (as many have mixed stories from various titles), but can provide that info if need be.
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Ballantine Books
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(Books that reprinted various stories)
Tales From the Crypt
Tales of the Incredible (sci-fi)
The Vault of Horror
The Autumn People (Bradbury reprints)
Tomorrow Midnight (Bradbury reprints)
Mad Reprint Books
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(Books reprinted Mad stories, published by both Ballantine and Signet)
The Mad Reader (two different printings)
Mad Strikes Back!
Inside Mad
Utterly Mad
The Brothers Mad
The Bedside Mad
Son of Mad
Horror Comics of the 1950's
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(Published in 1971, features reprints of approximately 20 stories, mostly horror but also some non-horror like Master Race and Squeeze Play)
One Volume Only
EC Library
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(Hardbound black & white library, generally 5-6 issues per volume)
Tales from the Crypt (Volumes 1-5) (includes the three issues of the Crypt of Terror)
Vault of Horror (volumes 1-5)
Haunt of Fear (volumes 1-5)
Shock SuspenStories (volumes 1-3)
Crime SuspenStories (volumes 1-5)
Weird Science (volumes 1-4)
Weird Fantasy (volumes 1-4)
Weird Science-Fantasy (volume 1)/Incredible Science Fiction (volume 2)
Mad (volumes 1-4) (both black & white and color editions exist)
Panic (volumes 1-2)
Two-Fisted Tales (volumes 1-4)
Frontline Combat (volumes 1-3)
Valor (one volume only)
Piracy (one volume only)
M.D. (one volume only)
Impact (one volume only)
Extra! (one volume only)
Psychoanalysis (one volume only)
Aces High (one volume only)
War Against Crime (volumes 1-2)
Crime Patrol (volumes 1-2)
Saddle Justice (one volume only)
Gunfighter (volumes 1-2)
A Moon, A Girl... Romance/Saddle Romances (one volume only)
Modern Love (one volume only)
Shock Illustrated (one volume only)
Crime Illustrated (one volume only)
Terror Illustrated (one volume only)
Confessions Illustrated (one volume only)
EC Portfolios
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(Russ Cochran reprints from original art, full size if I remember correctly)
Issues 1-6
East Coast Comix Reprints
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(32 page reprints of single issues
Issue 1: Tales From the Crypt #46
Issue 2: Weird Science #15
Issue 3: Shock SuspenStories #12
Issue 4: Haunt of Fear #12
Issue 5: Weird Fantasy #13
Issue 6: Crime SuspenStories #25
Issue 7: Vault of Horror #26
Issue 8: Shock SuspenStories #6
Issue 9: Two-Fisted Tales #34
Issue 10: Haunt of Fear #23
Issue 11: Weird Science #12(1)
Issue 12: Shock SuspenStories #2
EC Classics
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(magazine sized 64 page reprints, first 6 issues featured random stories from single title, last 6 issues featured reprints of 2 different issues in their entirety)
Issue 1: Tales From the Crypt
Issue 2: Weird Science
Issue 3: Two-Fisted Tales/Frontline Combat
Issue 4: Shock SuspenStories
Issue 5: Weird Fantasy
Issue 6: Vault of Horror
Issue 7: Weird Science-Fantasy
Issue 8: Crime SuspenStories
Issue 9: Haunt of Fear
Issue 10: Panic
Issue 11: Tales From the Crypt
Issue 12: Weird Science
Gladstone Reprints
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(64 page comics featuring 2 issues each. Crypt had Crime as the backup book. Vault had Haunt for the first 4 issues, and Weird Science for the last 2. Haunt had Weird Science-Fantasy as the backup for its two issues)
Tales From the Crypt 1-6
Vault of Horror 1-6
Weird Science 1-4
Haunt of Fear 1-2
RCP Reprints
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(64 page comics in similar format to Gladstone, Crypt had Crime as the backup book, Vault had Weird Science, and Haunt had Weird Fantasy)
Tales From the crypt 1-7
Vault of Horror 1-5
Haunt of Fear 1-5
Gemstone Publishing
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(reprinted pretty much everything except for Mad in 32 page format)
Tales From the Crypt 1-30
Vault of Horror 1-29
Haunt of Fear 1-28
Weird Science 1-22
Weird Fantasy 1-22
Weird Science-Fantasy 1-7/Incredible Science-Fiction 10-13
Crime SuspenStories 1-27
Shock SuspenStories 1-18
Frontline Combat 1-15
Two-Fisted Tales 1-24
Panic 1-12
Piracy 1-7
Valor 1-5
M.D. 1-5
Extra! 1-5
Psychoanalysis 1-4
Aces High 1-5
War Against Crime 1-11
Crime Patrol 1-11
(each title also had annuals composing of 5-6 issues each)
Tales Calculated to Drive You Mad
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(Published by DC in Magazine format, reprinted the first 23 issues)
Issues 1-8