Check it out, man, the same class on the second paragraph created an span with the attribute of the class:
Before:
<p class="noind">Non onono nono nonono,</p>
<p class="noind">nono nono nonono no no nono nonono no no no...</p>
After (same procedure as before):
<p class="noind">Non onono nono nonono,<br/><span style="text-indent: 0em;">nono nono nonono no no nono nonono no no no...</span></p>
When those <p> became ONE the SECOND one is not letting go its past.
Anyway, the Book View makes easier to compare the EPUB with the image of the book and to fix the formatting switching between the views. After all verified, I clean up these unnecessary styles that Sigil generates with find/replace (usually text-indent).
It is a very good and popular software and we try to report all supposed problems to make it always better. Without pressure, right?!