I just unpacked both mobis:
<p height="0pt" width="1em" align="justify">
for every paragraph
while original has
<p height="9em" width="0pt">
for the first paragraph.
Of course I could doctor the html in mobi instead of ePub, but my goal is to delete mobis and convert the ePub if I want to re-read.. That means I have to learn what changes work or I'll have exactly same issues in the future.
@DiapDealer - what conversion settings did you use?