uniquify-trailing-separator-p

uniquify-trailing-separator-p is a variable defined in `uniquify.el'.
Its value is

nil

Documentation:
If non-nil, add a file name separator to dired buffer names.
If `uniquify-buffer-name-style' is `forward', add the separator at the end;
if it is `reverse', add the separator at the beginning; otherwise, this
variable is ignored.

You can customize this variable.