2010-02-12_aaa,654
2010-02-12_aaa,248
2010-02-12_bbb,374
2010-02-12_ccc,158
2010-02-13_aaa,745
2010-02-13_bbb,786
2010-02-13_bbb,354
2010-02-13_ddd,852
2010-02-14_bbb,754
2010-02-14_aaa,169
2010-02-14_ccc,965
2010-02-14_ccc,756

##</code><code>##

2010-02-12_aaa,902
2010-02-12_bbb,374
2010-02-12_ccc,158
2010-02-13_aaa,745
2010-02-13_bbb,1140
2010-02-13_ddd,852
2010-02-14_bbb,754
2010-02-14_aaa,169
2010-02-14_ccc,1721

##</code><code>##

 use List::MoreUtils qw(uniq);

 my @unique = uniq( 1, 2, 3, 4, 4, 5, 6, 5, 7 ); # 1,2,3,4,5,6,7
 my $unique = uniq( 1, 2, 3, 4, 4, 5, 6, 5, 7 ); # 7