Hey smerrian,
If you are willing to invest a little time, you might be able to save some additional money on your two week rental - this trick sometimes works.
Check the price of 2 one week rentals and see if it improves your total by an amount acceptable enough to offset having to go to the rental car center in the middle of your trip to trade in one car and get another car. Sometimes you can even keep the original car if you like it.
This normally works if you are using a coupon that takes $x off on a weekly rental. It may not work in this case, but it may help someone else.
I learned this trick years ago from westie.
Hope this helps someone.
Cheers,
Deanna