Hi Luca,
Thanks for hopping in the forum. Currently, the plugin will only connect to one list at a time. If you’re trying to organize the subscribers in your MailChimp list, you might consider using groups. Groups can be added as checkboxes on your form. Then subscribers can pick the group they want to be added to. This guide from the MailChimp knowledge base can help with creating groups in your list: http://kb.mailchimp.com/article/what-is-a-group-and-why-would-i-want-to-set-one-up
Or if you’re trying to add two forms connected to the two lists to the site it’s best to add one using the plugin and add the other with the MailChimp embed code: http://kb.mailchimp.com/article/how-can-i-add-my-signup-form-on-my-website
Let us know if you have any other questions.
-mc_d
