When a document is located on a relative, look at the pages before and after the document for additional references to your relative. Deeds sometimes get recorded in "batches," when it is realized that they were forgotten. Children sometimes get baptized in groups when a minister finally arrives or someone decides it is time.
And occasionally there is a supplemental death certificate when a correction needs to be made.
Indexes will take you to a direct, exact page. It's up to you to turn a few pages before and after that page to see if there's an additional find.