Duplicate entry

PRIMARYSQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '2015-03-29 03:00:00' for key 'PRIMARY'Array
(
    [query] => INSERT INTO `Ox-NOx-Daten`  SET `Datum` = :setv0, `Zeit` = :setv1, `O3` = :setv2, `NOx` = :setv3, `NO2` = :setv4, `OX` = :setv5
    [prepare] => Array
        (
            [setv0] => 2015-03-29 02:00:00
            [setv1] => 02:00:00
            [setv2] => 14.0
            [setv3] => 6.94
            [setv4] => 5.42
            [setv5] => 19.42
        )

)