Duplicate keys, med lange keys

Jeg har et problem med følgende sql:

DROP TABLE IF EXISTS SearchIndexes;
CREATE TABLE SearchIndexes (
  SearchIndexChecksumHigh bigint(8) unsigned NOT NULL default '0',
  SearchIndexChecksumLow bigint(8) unsigned NOT NULL default '0',
  SearchIndexSoundEx int(5) unsigned NOT NULL default '0',
  SearchIndexText varchar(100) NOT NULL default '',
  KEY SearchIndexSoundEx (SearchIndexSoundEx),
  KEY SearchIndexText (SearchIndexText),
  PRIMARY KEY  (SearchIndexChecksumHigh, SearchIndexChecksumLow)
) TYPE=MyISAM;;

INSERT INTO SearchIndexes (SearchIndexChecksumHigh, SearchIndexChecksumLow, SearchIndexSoundEx, SearchIndexText) VALUES (17062952057979068416,2895972726640982771,808464432,'3');
INSERT INTO SearchIndexes (SearchIndexChecksumHigh, SearchIndexChecksumLow, SearchIndexSoundEx, SearchIndexText) VALUES (17062952057979069182,2895972726640982771,808464432,'3');


Selvom "SearchIndexChecksumHigh" er forskellige i disse 2 INSERT, så får jeg fejlmeddelsen:

Error: 1062
Duplicate entry '17062952057979068416-2895972726640982771' for key 1
INSERT INTO SearchIndexes (SearchIndexChecksumHigh, SearchIndexChecksumLow, SearchIndexSoundEx, SearchIndexText) VALUES (17062952057979069182,2895972726640982771,808464432,'3');

Jeg benytter MySQL 3.23.52