Dumpevt and trouble about records

normally, only log records added since the last execution of DumpEvt are dumped, but for me, every log are dumped ( I run the dumpevt with a batch and every day with a windows crontab)

batch :

for /F %%i in ('date /t') do set jour=%%i
c:\cyd\dumpevt.exe /logfile=sys /outfile="c:\cyd\%jour%%COMPUTERNAME%.system"
c:\cyd\dumpevt.exe /logfile=app /outfile="c:\cyd\%jour%%COMPUTERNAME%.application"
c:\cyd\dumpevt.exe /logfile=sec /outfile="c:\cyd\%jour%%COMPUTERNAME%.security"
c:\cyd\dumpevt.exe /logfile=rpl /outfile="c:\cyd\%jour%%COMPUTERNAME%.replication"
c:\cyd\dumpevt.exe /logfile=dns /outfile="c:\cyd\%jour%%COMPUTERNAME%.dns"
c:\cyd\dumpevt.exe /logfile=dir /outfile="c:\cyd\%jour%%COMPUTERNAME%.directory"

I use Somarsoft DumpEvt V1.7.3

Thanks for your help