Peak bitrate of the exported VOB files change radically

I have tested with Bitrate Viewer my timeline's .m2v file, its peak bitrate is a
bit under 8700Mbits. The project has one subtitle track, and two ac3 audio
tracks (2.0 track is 320kbps (Encore encodes the 2.0) and 5.1 is 448kbps). So,
as making peak bitrate calculations the maximum bitrate should not exceed
9.8Mbits, right? Still, when I'm viewing the exported DVD Folder with Bitrate
Viewer, VTS_01_1.VOB has a peak bitrate of 12723MBit. In that VOB the average
bitrate is around 7500 as it should and mostly max. 8200Mbits. How is this
possible that there is this single super peak in the VOB?

PS. Did another test, I changed the 2.0 AC3 track (which Encore encodes) to a
previously AC3 encoded track my client provided me, now two of the VOBs have
these super peaks as:

VTS_01_1.VOB - 11010Mbits
VTS_01_5.VOB - 13486Mbits

Tested also another commercial release, its VOB files have peaks going over
11400bits (VTS_01_0.VOB) and 10036bits (VTS_01_1.VOB) as well. So looks like
Bitrate Viewer isn't telling the truth when you view VOB files with it? Or that
these peak values mean something else? Bitrate Viewer can't be used to view the
VOB files and their peaks this way? What do the peak values of the VOB mean then
that Bitrate Viewer gives? As this commercial dvd's peaks are over 11Mbits as
well, which at least should be over the max peak value what the DVD-spec allows
to have for all the streams?

Quick nit-pick note.
Encore should not be encoding stereo AC3 to 320kbps.
Should be 192.