We are not having OOTB code to clone work object. To achieve this functionality what you could do is:
1 - Have a data page sourced with look-up.. pass the case pyID which information needs to be cloned as parameter to the data page and get all the case information.
2 - Now copy the needed information from data page into shadow page of the new work object class.
3 - After all the values copied to shadow page, call svcAddWorkObject activity with the step page of shadow page in which you have copied all information and pass the needed parameter to the activity. This will in turn creates a new work object with previous case information..