This seems to be a repeated question. We will answer in the original thread found here: http://wordpress.org/support/topic/multiple-use-of-email-before-download-and-contact-form-1?replies=2#post-4980037
The answer we gave there is below. Thank you for your understanding.
Thank you for your interest in our plugin. You will just need to create multiple contact forms and use a different CF7 id in the Email Before download shortcode.
[email-download download_id="X" contact_form_id="Y"]
For example, Y will be different based on the contact form you want to use. If you want to use the same contact form, but a the user will download different files, change the "x" to match the desired download ID.
Let us know if you have any more issues.