Theme search-result pages individually? We can theme the search-result pages within search-results.tpl.php and search-result.tpl.php. But as far at it is possible to create multiple search pages(e.g. in apache solr module), is it possible to theme each page individually?

Example: 

search-results--page1.tpl.php
search-results--page2.tpl.php
It is possible.

Apache solr search module introduced tpl files for each search page.

If your custom search page's machine name is simple search, the search results tpl for that page will be named as 

    search-results--apachesolr-search--simple-search.tpl.php


Replace simple-search with the machine name of your search page, with underscores converted to hyphens.