How to add two registration form on single page?
Give a try to Profile2 Registration Path module:

Problem with Profile2 module: By default, the Profile2 module permits you to add fields from chosen profile types to the default user registration form. Unfortunately, there is only one user registration form. Thus, every user will be presented with these fields during registration. If you have two profile types targeted at two different audiences, you cannot have two separate registration forms.

Solution: 


  Profile2 Registration Path enables you to set a unique registration path for each Profile2 profile type. Users who register via that unique path will be presented with fields from the chosen profile type(s).




Alternatively another method to include multiple forms (e.g: FORM1 and FORM2) on same page is somewhat like below(however I am not sure where it will work with the profile2 forms):

$output = array();
$output['FORM1_DISPLAY'] = drupal_get_form('FORM_1_FORM_ID');
$output['FORM2_DISPLAY'] = drupal_get_form('FORM_2_FORM_ID');
return $output;