Facebook only allows one Leadpages tab per Facebook Page. While you can only publish one Leadpage on a Facebook Page, you do have additional options for gathering opt-ins on Facebook, as follows:
Option 1: Add a Facebook Call-To-Action button.
PLEASE NOTE: Leadpages templates are mobile responsive, so there's no need to provide a Mobile Website in the box shown below.
Option 2: Add Leadpages tabs to multiple Facebook Pages.
You can create a Leadpages tab (using the same or different Leadpages) on as many of your Facebook pages as you wish. Simply follow the instructions in our article on Publishing to Facebook here, and select you particular Facebook page in "Step 3".
Please let us know if you have additional questions.
You can always file a support ticket if you have additional questions by clicking the Support button in your dashboard shown here or clicking here to file a support ticket.