That is because Own is the translator, so he is acknowledged alongside the author, Calvin.

oh okay thank you I now see this. The only issue is it gets confusing as both this John Owen from the 19th century and the more famous John Owen, Puritan from the 17th century, are both categorized as the same person when you search under John Owen under the author category of your library search bar. I wish there were a way to differentiate them in the author category.