Fix checksuming check when same checksums are not in adjacent lines

sample result
DATABASE TABLE CHUNK HOST      ENGINE      COUNT         CHECKSUM TIME WAIT STAT  LAG
test     t1        0 127.0.0.1 InnoDB          2         f54c7385    0    0 NULL NULL
test     t1        0 127.0.0.1 InnoDB          2         xxxxxxxx    0    0 NULL NULL
test     t1        0 127.0.0.1 InnoDB          2         f54c7385    0    0 NULL NULL
test     t1        0 127.0.0.1 InnoDB          2         f54c7385    0    0 NULL NULL