The Virtual User name is used as a prefix for all transactions and methods scripted in BDL. This is necessary to prevent method-name duplication, since the same method name may exist in two different .NET classes.
The engine checks for duplicate Virtual User names. If the assembly contains more than one Virtual User class, the names passed as parameters to the VirtualUser attribute must be unique. If there are duplicate names, an error is thrown and shown in the task list.