Hi Bruce,
There is no simple answer for if copying a workflow is a bad idea or not. For example, when you want to "enhance" a SAP standard workflow, copying it is the right approach. Normally copying is a valid option. But then it is quite important that what you do for the workflow afterwards. I would advice that do not delete anything from the workflow template unless you are absolutely sure what you are doing (=you should have good understanding of the copied workflow). And as Jocelyn mentioned, you need to remember that if you do changes to the underlying objects (tasks, methods, etc.) that the workflow is using, you must remember that the old workflow is still using the existing objects, and it you change them, the old workflow might face problems. => Be careful!
Anyway, I am not sure if your copying is the cause for the problem. It might be, but it might not (especially when the workflow is working in the development system). You might want to create some of the objects (that are causing problems) again, and/or doing some new transports etc.
Regards,
Karri
PS. If you run the check for the workflow template (in SWDD) in the test system, does it find any errors/warnings (visible in the bottom of the screen)? Maybe this is obvious, but worth to check. You might be missing some object in the test system (since the objects are tied to another transports etc.)