Unfortunately you cannot get 2 early birds since Kickstarter only allows one choice. If you want to get 2 early birds, you will have to create a different account. I would also suggest you pledge for the $69 two-pack since this also has a great discount.
Firstly, Passport GO has 30W Power Delivery with GaN while Passport Pro has 18W Power Delivery. Secondly, Passport GO is compatible with more countries than Passport Pro. Thirdly, Passport Pro has a separated EU adapter while there is not for Passport GO. Fourthly, Passport Pro is grounded and Passport GO is not.