Same ISBN, different publisher?

[Penelope]

I have a copy of this book (same ISBN as above), but the publisher of my copy is not Viking Penguin, but Stephen Greene Press. Additionally, mine says:
Published September 1965
Reprinted thirteen times, 1965 through 1977
Fifteenth printing August 1978
223,000 copies in print

Is there a specific policy on how to handle books with the same ISBN but different publishers?

[Beth]

Viking and Stephen Greene Press are both part of Penguin Group; the info was imported by Ingram. I've changed it to Stephen Greene Press, per your copy and WorldCat's records.

[Emy]

Stephen Greene and Viking both belong to Penguin now, so it's probably that they published it, and so did Viking, and that the ISBN is that of the overarching group.

PENGUIN GROUP: Allen Lane, Alloy Books, Bibli O'phile, Cobblehill, Dial Books for Young Readers, Discovery Kids, DreamWorks, Dutton, Dutton Children's, Donald I. Fine Hardcovers, Frederick Warne, Gotham, HighBridge Audio, Library of America, Lodestar, Mermaid, Michael Joseph, Mobil Travel Guides and Books, The Monacelli Press (all formats), The Overlook Press (adult hardcovers and all children's), Pelham, Penguin AudioBooks, Penguin HighBridge Audio, Penguin Music Classics, Penguin Reference, Penguin Studio, Phyllis Fogelman, Portfolio, Puffin, Puffin Classics, Rough Guides, Stephen Greene Press, Viking, Viking Arkana/Compass, Viking Children's Books, and Viking Studio.