Yes, that’s correct. You can use the same ISBN for KDP and Ingram Spark as long as the book is the same print format (e.g., paperback with the same size and content). eBooks do not require ISBNs, and most authors don’t use them. If used, different digital formats technically need separate ISBNs, but this is rarely enforced. Audiobooks also do not require ISBNs and use platform-specific identifiers instead. In short: Same print format across platforms: same ISBN Different formats (paperback, hardcover): new ISBN eBook and audiobook: ISBN not required