Filefield Meta Duplicate entry Error when using getID3 module

Uploading mp3 file and using getID3() with filefield meta causes error

user warning: Duplicate entry '21' for key 1 query: INSERT INTO filefield_meta (fid, width, height, duration, audio_format, audio_sample_rate, audio_channel_mode, audio_bitrate, audio_bitrate_mode, tags) VALUES (21, 0, 0, 255.9739, 'mp3', 44100, 'joint stereo', 160000, 'cbr', 'a:8:{s:5:\"title\";s:14:\"Black or White\";s:12:\"track_number\";s:2:\"03\";s:4:\"year\";s:4:\"1995\";s:5:\"genre\";s:3:\"Pop\";s:10:\"encoded_by\";s:5:\"AIMP2\";s:6:\"artist\";s:15:\"Michael Jackson\";s:5:\"album\";s:7:\"History\";s:25:\"content_group_description\";s:3:\"CD1\";}') in .../includes/common.inc on line 3538.

Nevertheless, the filefield meta record with fid 21 is created and is ok. what causes the error and how to solve it not to appear, as everything else works correct.

Thank you.