i have duplicate errors with CPU miner by the way...
you are the first person with such problem then. it's well known gpu-miner issue, but not cpu-miner one
can you show us log? and please tell which binary are you using, downloaded from where exactly, what OS etc.
webchain miner CPU miner 2.6.2.0 (size 932kb). It doesn't create log files (turned off in config by default). I change false to true but doesnt see any log files.