Use in your mod_your_module.php the folowing:
$layout = $params->get('layoutChoice');
require(JModuleHelper::getLayoutPath('mod_your_module', $layout ));
Then in your mod_your_module.xml write this:
<field name="layoutChoice" type="list" default="default" label="mod_layout_choice" description="mod_layout_choice_description" >
<option value="default">default</option>
<option value="default2">default2</option>
<option value="default3">default3</option>
<option value="default4">default4</option>
</field>
Then make sure that corresponding files default.php ,default2.php, default3.php, default3.php are in your module /tmpl directory.
That configuration work for Joomla 2.5.
Doing it in that way, you can choose your different template from administration menu of module in advanced or basic section depend where you write above in your_module.xml file.
You can prolong above configuration writing in mod_your_module.xml file the flowing:
<field name="layoutChoice" type="list" default="default" label="MOD_LAYOUT_CHOICE" description="MOD_LAYOUT_CHOICE_DESC" >
<option value="default">MOD_LAYOUT_CHOICE_DEFAULT</option>
<option value="default2">MOD_LAYOUT_CHOICE_DEFAULT2</option>
<option value="default3">MOD_LAYOUT_CHOICE_DEFAULT3</option>
<option value="default4">MOD_LAYOUT_CHOICE_DEFAULT4</option>
</field>
And then write in your en-GB.mod_your_module.ini the folowing:
MOD_LAYOUT_CHOICE="Choose which Template to Use"
MOD_LAYOUT_CHOICE_DESC="Your discription for each template is written hire"
MOD_LAYOUT_CHOICE_DEFAULT="First Template"
MOD_LAYOUT_CHOICE_DEFAULT2="Second Template"
MOD_LAYOUT_CHOICE_DEFAULT3="Third Template"
MOD_LAYOUT_CHOICE_DEFAULT4="Forth Template"