Thanks for the response.  I am not troubled by the different surnames.  In the late 18th century, when surnames were a new phenomenon for Jews in Lithuania due to laws that had been passed, it was not uncommon for siblings to take different surnames.  My concern is the given names - two “brothers” with essentially the same given name.  The 1834 Revision list identifies my fourth-great-grandfather as the brother of Meyer Soloveitchik and son if Itsik.  The listing contains a specific note - “brother of Meyer Soloveitchik.”. Meyer Soloveitchik was indeed the son of Yitzhak, seemingly cooborating the notation that Movsha Shames was the son of Yitzhak.  We know that Meyer Soloveitchik was also the brother of Moshe Soloveitchik, rabbi of Kovno in the late 1700s.  Putting this all together suggests that Movsha Shames and Moshe Soloveitchik were brothers.  So my question comes back to the Ashkenazi practice of not giving siblings the same given name - is there an explanation for Movsha Shames and Moshe Soloveitchik being actual brothers, or is there another twist - i.e., they were half-brothers, or Movsha Shames was adopted and/or a foster child, etc.