warning on edit type text - duplicate column

Edited text type and changed it from plain text to input filter. Got the following warning, although the setting was saved:

Saved field Description.
user warning: Duplicate column name 'field_description_format' query: content_db_add_column ALTER TABLE node_data_field_description ADD COLUMN field_description_format int(10) unsigned NOT NULL default 0 in /var/www/drupal/includes/database.mysql.inc on line 120.