I'm using a sample schema like this:

---
SlugI18nTest:
  actAs:
    I18n:
      fields: [title, content]
      actAs:
        Sluggable:
          fields: [title]
  columns:
    title: string(255)
    content: string

If executing the following code

for($i=0; $i<3; $i++) {
	$t = new SlugTemplateTest();
	$t->Translation['en']->title = 'Title';
	$t->Translation['en']->content = 'Content';
	$t->save();
	
	echo $t->Translation['en']->slug.'<br/>';
}

the resulting output is

title
title-1
title

expected was

title
title-1
title-2

I dug a bit through the code, and it seems that in the following code snippet from the "Doctrine_Hydrator" class is causing the problem. The result it returns to the Sluggable template only contains the last slug it found instead of all.

// do we need to index by a custom field?
if ($field = $this->_getCustomIndexField($rootAlias)) {
    if (isset($result[$field])) {
        throw new Doctrine_Hydrator_Exception("Couldn't hydrate. Found non-unique key mapping.");
    } else if ( ! isset($element[$field])) {
        throw new Doctrine_Hydrator_Exception("Couldn't hydrate. Found a non-existent key.");
    }
    $result[$element[$field]] = $element; /* << here previous results are overwritten */
} else {
    $result[] = $element;
}

I also will add a test case.