Generate a new Sub Plan/Sequence ID in SQL 2005/8 Business Intelligence Development Studio
Look at BIDSHelper. Fantastic, free tool everyone developing SSIS and probably SSAS should be using.

Reset GUIDs

"This feature resets the IDs for all tasks, connection managers, configurations, event handlers, variables, and the package ID itself. When you copy a package, objects in both packages end up with the same IDs. This Reset GUIDs feature ensures that the IDs in the current package are unique."