The log files are rotated once a VM is powered on and/or once the file reaches a certain size. The vmware.log (without a number) is the current log file. The old files are kept for troubleshooting purposes by default. You can - although I don't recommend it - disable this behavior or even configure the VM to not create any log files at all.
PS: Forgot to attach the KB article: http://kb.vmware.com/kb/8182749