Free Trial subscription automatically added to paid subscription member


I’m using Membership Premium 2.1.4, Buddypress 1.5.4 and WordPress 3.3.1

I have two Membership subscription levels: free trial and paid. When a user signs up for the paid “premium” subscription, they are assigned to it, but they are also assigned to the regular free trial subscription.

Is that supposed to happen? I can’t see where it’s getting set in the admin screens. They are two separate subscription plans, with two separate membership levels as starting points. I didn’t expect them to have a sequential relationship. How can I configure the plugin so that the free and the trial subscriptions are two separate entities with separate levels? I’d like users to have either one or the other, not both.