I don't understand this output

[james]

Hello, I don't understand why this results in the output it does.
I wanted to have the second voice instantiated in the beginning because it is 
used later and I would like to have the lyrics align vertically.
Alternatively, I thought to use \addlyrics after each little section of lyrics, 
but the polyphony is skewed after that.
Is the only possibility to use spacer rests?

\version "2.18.2"

\score {
   <<
      \new Staff <<
         \new Voice = "testII" { s1*2 }
         \new Voice = "testI" \relative c'' {
               c4 b <<{\voiceOne d8 b } \context Voice = "testII" {\voiceTwo 
a4} \context Lyrics = "testIIText" \lyricsto "testII" \lyricmode { di } >> 
\oneVoice>
               f4 e d c
         }
      >>
      \new Lyrics \lyricsto "testI" \lyricmode { du du da da du dum dum dum dum 
}
   >>
   \layout {}
}

\score {
   <<
      \new Staff {
         \new Voice = "testI" \relative c'' {
            c4 b <<{\voiceOne d8 b } \new Voice = "testII" {\voiceTwo a4} \new 
Lyrics = "testIIText" \lyricsto "testII" \lyricmode { di } >> \oneVoice g4
            f4 e d c
         }
      }
      \new Lyrics \lyricsto "testI" \lyricmode { du du da da du dum dum dum dum 
}
   >>
   \layout {}
}

\score {
   <<
      \new Staff <<
         \new Voice = "testI" \relative c'' {
            c4 b \voiceOne d8 b \oneVoice g4
            f4 e \voiceOne a8 g \oneVoice c,4
         }
         \new Voice = "testII" \relative c'' {
            \voiceTwo
            s2 a4 s4
            s2 d,4 s4
         }
      >>
      \new Lyrics \lyricsto "testI" \lyricmode { du du da da du dum dum dum dum 
}
      \new Lyrics \lyricsto "testII" \lyricmode { di dee }
   >>
   \layout {}
}