dot_three error

RPX03232014.3: Duplicate HorseName row 2 & 3
   Track      Date  RaceNum DayFlag            HorseName ForeignBred StateBred ProgNum  WinPO  PlacePO  ShowPO         race_id
0     RP  20140323        1       D        Mean Ole Lady         NaN        OK       1    4.4      2.4     2.1   20140323_RP_1
1     RP  20140323        1       D        Annie Laveaux         NaN        OK       6    NaN      3.4     2.4   20140323_RP_1
2     RP  20140323        1       D        Texas Tom Cat         NaN       NaN       8    NaN      NaN     3.8   20140323_RP_1
3     RP  20140323        1       D        Texas Tom Cat         NaN        OK       8    NaN      NaN     3.8   20140323_RP_1
4     RP  20140323        2       D     Corona Firewater         NaN        OK       3   19.2      4.0     4.8   20140323_RP_2
5     RP  20140323        2       D          Fly Sam Fly         NaN        OK       1    NaN      7.4     5.0   20140323_RP_2
6     RP  20140323        2       D        Separate Fame         NaN        OK       9    NaN      NaN     3.2   20140323_RP_2