Concat cutting audio length

[MrShakes]

I have 2 audio files: audio1.ogg and audio2.ogg and then I run

audioconcat(songArr)
    .concat(storyName + '.ogg')
    .on('start', function (command) {
      console.log('ffmpeg process started:', command)
    })
    .on('error', function (err, stdout, stderr) {
      console.error('Error:', err)
      console.error('ffmpeg stderr:', stderr)
      res.send({message: "Error"});
    })
    .on('end', function (output) {
      console.error('Audio created in:', output)
      makeVid(body, res);
    })

songArr has both audios in there and in the log I can see

ffmpeg process started: ffmpeg -i concat:audio1.ogg|audio2.ogg -y -acodec copy storyName.ogg

However when I play the finished audio, the second audio has been cut in half from about 16 seconds to just 8.

audioconcat version: ^0.1.3
node version: 6.10.2
npm version: 3.10.10
ffmpeg version 3.4.1