Latex beamer not allow 'label=' when 'allowframebreaks' setted in frame.
In file ox-beamer.el function org-beamer--format-frame search
'allowframebreaks' option inside beamer-opt but not inside variable
org-beamer-frame-default-options. Then insert 'label=..' with
'allowframebreaks' and latex hide continuation's frames.
Best regards. Héctor
Emacs : GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw scroll bars)
of 2018-05-30
Package: Org mode version 9.1.14 (9.1.14-7-g01c419-elpaplus @ /home/edo/.emacs.d/elpa/org-plus-contrib-20181015/)