Franz Tunder and Dieterich Buxtehude: father in law and son in law. Besides that Buxtehude succeeded Tunder as organist of the Marienkirche in Lübeck. So they were linked by musicianship and family bonds, as often in that time.
These two canzonas not only share the same key, but also the same structure and even some musical ideas. Could it be that Dieterich wrote an hommage to Franz...?