Samsung has apparently patented a type of display that extends over at least one edge of a smartphone's body onto its reverse side. LetsGoDigital asserts that the document it found on the subject suggests a number of applications for this tech. They may include switching 1 set of cameras between 'selfie' and 'main' modes.
https://www.notebookcheck.net/Flexible-but-not-foldable-Samsung-allegedly-patents-an-overlapping-display-for-smartphones.420123.0.html
Edge technology was first seen on the Galaxy Note 4 Edge, not the S6.