在本地做的网站，有时打开页面后，有些错误提示。当刷新一下页面后，又正常了。这是什么原因？

# user warning: Duplicate entry 'themes/garland/garland.info' for key 'PRIMARY' query: INSERT INTO system (name, owner, info, type, filename, status, throttle, bootstrap) VALUES ('garland', 'themes/engines/phptemplate/phptemplate.engine', 'a:13:{s:4:\"name\";s:7:\"Garland\";s:11:\"description\";s:66:\"Tableless, recolorable, multi-column, fluid width theme (default).\";s:7:\"version\";s:4:\"6.15\";s:4:\"core\";s:3:\"6.x\";s:6:\"engine\";s:11:\"phptemplate\";s:11:\"stylesheets\";a:2:{s:3:\"all\";a:1:{s:9:\"style.css\";s:24:\"themes/garland/style.css\";}s:5:\"print\";a:1:{s:9:\"print.css\";s:24:\"themes/garland/print.css\";}}s:7:\"project\";s:6:\"drupal\";s:9:\"datestamp\";s:10:\"1260996916\";s:7:\"regions\";a:5:{s:4:\"left\";s:12:\"Left sidebar\";s:5:\"right\";s:13:\"Right sidebar\";s:7:\"content\";s:7:\"Content\";s:6:\"header\";s:6:\"Header\";s:6:\"footer\";s:6:\"Footer\";}s:8:\"features\";a:10:{i:0;s:20:\"comment_user_picture\";i:1;s:7:\"favicon\";i:2;s:7:\"mission\";i:3;s:4:\"logo\";i:4;s:4:\"name\";i:5;s:17:\"node_user_picture\";i:6;s:6:\"search\";i:7;s:6:\"slogan\";i:8;s:13:\"primary_links\";i:9;s:15:\"secondary_links\";}s:7:\"scripts\";a:1:{s:9:\"script.js\";s:24:\"themes/garland/script.js\";}s:10:\"screenshot\";s:29:\"themes/garland/screenshot.png\";s:3:\"php\";s:5:\"4.3.5\";}', 'theme', 'themes/garland/garland.info', 0, 0, 0) in F:\php\jh28\modules\system\system.module on line 822.
# user warning: Duplicate entry 'themes/chameleon/marvin/marvin.info' for key 'PRIMARY' query: INSERT INTO system (name, owner, info, type, filename, status, throttle, bootstrap) VALUES ('marvin', '', 'a:13:{s:4:\"name\";s:6:\"Marvin\";s:11:\"description\";s:31:\"Boxy tabled theme in all grays.\";s:7:\"regions\";a:2:{s:4:\"left\";s:12:\"Left sidebar\";s:5:\"right\";s:13:\"Right sidebar\";}s:7:\"version\";s:4:\"6.15\";s:4:\"core\";s:3:\"6.x\";s:10:\"base theme\";s:9:\"chameleon\";s:7:\"project\";s:6:\"drupal\";s:9:\"datestamp\";s:10:\"1260996916\";s:8:\"features\";a:10:{i:0;s:20:\"comment_user_picture\";i:1;s:7:\"favicon\";i:2;s:7:\"mission\";i:3;s:4:\"logo\";i:4;s:4:\"name\";i:5;s:17:\"node_user_picture\";i:6;s:6:\"search\";i:7;s:6:\"slogan\";i:8;s:13:\"primary_links\";i:9;s:15:\"secondary_links\";}s:11:\"stylesheets\";a:1:{s:3:\"all\";a:1:{s:9:\"style.css\";s:33:\"themes/chameleon/marvin/style.css\";}}s:7:\"scripts\";a:1:{s:9:\"script.js\";s:33:\"themes/chameleon/marvin/script.js\";}s:10:\"screenshot\";s:38:\"themes/chameleon/marvin/screenshot.png\";s:3:\"php\";s:5:\"4.3.5\";}', 'theme', 'themes/chameleon/marvin/marvin.info', 0, 0, 0) in F:\php\jh28\modules\system\system.module on line 822.