Drupal 7 - Create a custom template that can be assigned to different pages
See here Drupal 7 Theme Hook Suggestions

For nodes You can use 

    node--[type|nodeid].tpl.php
    base template: node.tpl.php
    Theme hook suggestions are made based on these factors, 
listed from the most specific template to the least. 
Drupal will use the most specific template it finds:

    node--nodeid.tpl.php
    node--type.tpl.php
    node.tpl.php


Also Drupal 6 Template Suggestions

To use same tpl for multiple pages you need to use theme_preprocess_node
Like

function theme_preprocess_node(&amp;$vars, $hook) {
  $node = $vars['node'];
  if(in_array($node-&gt;nid), $myuids)
   $vars['template_file'] = 'your_template_file';
}