Q. In MLA format, if my sources are pages from the same book, do I have to list the book twice in my work cited list?

No, you can use the same source more than once, and only list it a single time in your Works Cited page. Your in-text citation provides the page number information. 

The citation in the body of your paper for a book will include the author or authors' last name(s) and the page number. If you mention the author(s) in the sentence, just put the page number in the (). If not, use the last name and page number.

Whether or not you place the in-text citation at the end of the sentence or within the sentence depends on if you use a direct quote or paraphrase.

The reference in your Works Cited page will include page numbers only if the book is an anthology or collection.