Your licence allows for up to two machines "that are not typically in use at the same time." So if that statement covers your situation then you should be alright. It was made with work/home, work/laptop... and so on in mind.
If it is for you and your child that will be using it constantly then one or two licences at this time does not qualify for a discount I am afraid. Bulk purchases of large numbers do. However it is still best to inquire to sales to see if any speical discounts are coming up or any promotions will be available soon.