Dealing with Loop

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Hi everyone!
After reading lot of posts and solutions, I haven’t found the one which fits well to my “trouble”. Here is:
I want to have the three lasts post of a category (Titular) in my home, but this way:
<div id=”num1″>
LAST POST (i.e. post number 50)
</div>

<div id=”num2″>
PENULTIMATE POST (i.e. post number 49)
PENULTIMATE’S PREVIOUS POST (i.e. post number 48)
</div>

I’ve been reading a lot in this posts but I don’t have what I’m doing wrong:
For the first div:
<div id=”num1″>
<?php $do_not_duplicate[] = $post->ID; ?>
<h2 id=”post-<?php the_ID(); ?>”>
<?php the_title(); ?></h2>
<p>“>Ver artículo</p>
</div>

And for the second one:
<div id=”num2″>
<?php
query_posts(array (‘posts_per_page’ => 3, ‘post__not_in’ => $do_not_duplicate) );
if (have_posts()) :
while (have_posts()) : the_post();?>
<h3 id=”post-<?php the_ID(); ?>”>
<?php the_title(); ?></h3>
<?php the_excerpt(); ?>
<?php endwhile; ?>
</div>

And I have a first area with the last post’s title and “Ver artículo”, and a second area with the three last post. This last issue is wrong, becasue I want the two previous posts to last one.

Please help me! I’m getting mad 🙁

Thanks in advance