Originally Posted by
notacolour
Unlike airline tickets even the discounted advance purchase tickets are still fully refundable, which is why people here will recommend that you buy early even if you're not completely sure when you want to travel--because you can always cancel.
If you've been able to have them refunded for cash, as opposed to credit, you're getting lucky. The terms for the NE corridor advanced discount explicitly state "Non-refundable. Exchanges permitted for other rail fare purchases."