Zend certified PHP/Magento developer

Importing Customer list errors

Was importing a file when these errors were identified, not sure what they mean exactly

Duplicates found in column names: array ( 0 => ”, 1 => ‘mail,_w’, 2 => ‘bsit’, 3 => ‘,_stor’, 4 => ‘,confirmation,cr’, 5 => ‘at’, 6 => ‘d_at,cr’, 7 => ‘at’, 8 => ‘d_in,disabl’, 9 => ‘_auto_group_chang’, 10 => ‘,dob,firstnam’, 11 => ‘,g’, 12 => ‘nd’, 13 => ‘r,group_id,lastnam’, 14 => ‘,middl’, 15 => ‘nam’, 16 => ‘,password_hash,pr’, 17 => ‘fix,rp_tok’, 18 => ‘n,rp_tok’, 19 => ‘n_cr’, 20 => ‘at’, 21 => ‘d_at,stor’, 22 => ‘_id,suffix,taxvat,updat’, 23 => ‘d_at’, )

Need help understanding what I am missing.