I have heard that taking a second pill does nothing more than the first one would have been able to accomplish. Your girlfriend can check with her gynecologist regarding the effectiveness of the second pill, however, I'm pretty sure doubling up on the pill, in this case, is worthless. If anything, she will be one pill short at the end of her pack and that pill will constitute as a "missed pill" since she will not be able to take it. Even though I am certainly no doctor, I would suggest using condoms as a backup means of birth control for a week after she misses the pill (the pill she should have taken the following day, rather than at the same time as her other).
I have talked to a nurse about this because I, too, have been in a very similar circumstance and very recently at that. You should be fine. An hour and x odd minutes should not affect the effectiveness of the pill if she has been taking her pills on time, as directed. There is always a chance of pregnancy when having sex because the pill alone is not 100 percent effective. Even at it's 99.99%, there is still that %.1 that lingers in the air -- which is why abstinence is really the only 100% effective means to preventing pregnancy. If you wish to eliminate future worries, I would suggest using a condom as well. When used correctly, condoms are just about as effective as the birth control pill. If used at the same time as the pill, your chances of pregnancy are pretty much impossible.
She should be fine, but it IS important to take your pill at the same time every day.
You could have her call her gynecologist just to be safe.