Spurious warning about simultaneous dynamics

[Dan Eble]

\version "2.19.58"

%% engrave dynamics in Staff context
\layout {
  \context {
    \Staff
    \consists "Dynamic_engraver"
    \consists "Dynamic_align_engraver"
  }
  \context {
    \Voice
    \remove "Dynamic_engraver"
    \remove "Dynamic_align_engraver"
  }
}

%% This causes a warning, yet the output looks fine.
%% warning: Two simultaneous absolute-dynamic events
<< b'\f \\ <g'>\f >>

%% Both of these look the same as the above yet cause no warning.
<< b'\f \\ g'\f >>
<< <b'>\f \\ <g'>\f >>

%% If Lilypond somehow knows that the latter cases are fine, it would
%% be nice if it would also keep quiet about the first case.
%%
%% Regards,
%% Dan