Yes they are, because when you go to sign the final agreement, it would supercede the prior one, and once you sign that one, the prepurchase agreement is voided.
But let's say you catch that before you sign the final agreement and refuse to do so. Then you look at what the terms are for either party for defaulting on the original prepurchase agreement. In this case, it's refunding you the order fee/deposit and any prior paid fees.
This is generally the case for preorders for any product in general. At most the retailer owes to back the preorder fee (in some jurisdictions maybe interest on the fee), but nothing else. There are some people that think instead by preordering, the retailer is now bound to deliver the product at the given price, no matter what (as if a court would order them to do so), but the reality is you were made "whole" already by the refunding of your money and the retailer owes nothing else in damages, if not agreed to prior.