Setting offline one site cause another independent also offline

I have here another problem, it seems it has the same root.

I have 2 independent drupal sites, installed separatly:
1) URL = example.com , folder=/opt/example.com , database = example_db
2) URL = test.example.com , folder=/opt/test.example.com , database = test_example_db
Both websites work with caching : APC,memcached

Both websites have the same module "testmodule".
In testmodule.module ot the website test.example.com I add:

function testmodule_theme($existing, $type, $theme, $path) {
return array(
'user_profile_form' => array(
'arguments' => array('form' => NULL),
'template' => 'user-profile-edit',
),
);
}

So this must apply only to website test.example.com.
But I have a problem on example.com, it says that it cannot find file "user-profile-edit.tpl.php".

It seems to be a real problem, if Drupal mix someway different sites in one scope and use configuration from one site for another independent one.

The problem was in configuration of memcache.
It disappeared when i added in configuration file :
'memcache_key_prefix' => 'unique_prefix',