Porringers were often produced in sets of two to six.  Over the years most sets were divided, and today they are known only through manuscript references. The Bayou Bend example was originally one of a set of at least three. 

Related examples:  The Bayou Bend porringer's engraved initials indicate it was originally part of a set with one now at RISD (acc. no. 22.110), and another was auctioned by Parke-Bernet Galleries, New York, sale 2919, October 28, 1969, lot 132. Kane 1998 lists thirty-one porringers from the John Burt shop.

Book excerpt: David B. Warren, Michael K. Brown, Elizabeth Ann Coleman, and Emily Ballew Neff.  American Decorative Arts and Paintings in the Bayou Bend Collection. Houston: Princeton Univ. Press, 1998.