Dear admin why sometimes i get half coins exchanged when there is no point?

2014-06-10 14:30:46    Exchanged    MHYC    0.67887623    2014-06-10 14:31:05    0.00000000 BTC    0.00000000 BTC    2014-06-10 15:15:05

2014-06-10 15:00:09    Exchanged    GRN    0.18333703    2014-06-10 15:00:35    0.00000000 BTC    0.00000000 BTC    2014-06-10 15:14:53

Whats the point of exchanging half a coin for zero bitcoins?