Great question. This is something that occurs fairly often in the Herencia collection, due to the way it was originally organized and scanned. A single scanned image can sometimes contain the last page of one document on one side and the first page of a second document on the opposite side. In a few cases, we even see multiple, brief "documents" on a single page, with each of them treated as a separate item for cataloging and presentation purposes, even if the image is the same.
In all of these cases, our advice is to transcribe exactly what you see, even if it means transcribing something that isn't technically part of the document that is identified by the title above. If the transcription was already completed in another document that you find, please feel free to copy and paste that transcription and just review the text and make any changes as needed.