Hi
There is one workitem (the last step in your workflow) going to multiple users (two in your case).
It is a default design of workflows that if a work item goes to multiple users, the the first one to get to it reserves it (automatically). If it is is executed by that user, it finishes.
If you want that it should not end until all assigned users execute it, you will have to implement dynamic parallel processing:
http://help.sap.com/saphelp_470/helpdata/en/6f/04683cf5e8fe67e10000000a114084/content.htm
Dynamic Multilevel approval Workflow using Block Step
**************** - Dynamic Parallel Processing in Workflow
regards,
Modak
