Cannot redeclare class SphinxClient

After installation, I've got a blank page with next error: 'Cannot redeclare class SphinxClient in /home/user/www/sites/all/modules/sphinx/includes/api/sphinxapi.php on line 379'. I've delited sphinxapi.php, reload page and got a message 'Sphinx module installed'. Then I placed sphinxapi.php in /home/user/www/sites/all/modules/sphinx/includes/api and put a debug_print_backtrace() at the top of sphinxapi.php, and have got the next:

#0 include_once() called at [/home/user/www/sites/all/modules/sphinx/sphinx.module:19]
#1 include_once(/home/user/www/sites/all/modules/sphinx/sphinx.module) called at [/home/user/www/includes/bootstrap.inc:707]
#2 drupal_load(module, sphinx) called at [/home/user/www/includes/module.inc:14]
#3 module_load_all() called at [/home/user/www/includes/common.inc:2672]
#4 _drupal_bootstrap_full() called at [/home/user/www/includes/bootstrap.inc:1203]
#5 _drupal_bootstrap(8) called at [/home/user/www/includes/bootstrap.inc:1110]
#6 drupal_bootstrap(8) called at [/home/user/www/index.php:16]
Fatal error: Cannot redeclare class SphinxClient in /home/user/www/sites/all/modules/sphinx/includes/api/sphinxapi.php on line 379