Batch Enrollment and Default Plan

We have several Plans on our 401K Category in Benefits by Benefit Group.  One of the Plans is set as the default.  My understanding is that if the employee is enrolled in an existing 401k Plan they would not be enrolled in thie Default Plan we setup.  However, when we run the Batch Enrollment it is trying to enroll them in the Plan even if they are enrolled in a 401K Plan.  Did I miss something in my setup or documentation?

Thank you.

Pat