Boiling 60 minute recipe for 120 minutes

So I am doing my first all grain brew and wound up with too much wort after my 60 minute boil so I'm doing another 60 minutes.

I realize this will impart more of the hop profile to the beer beyond what the recipe intended.. what else?

Is my beer going to be awful?

This is the recipe I used

https://www.homebrewtalk.com/f69/imperial-ipa-93196/

Ultimately, I would leave it alone. If your gravity is way low, adjust with malt extract. If you're gravity is close but you can't fit it in your fermentor, so what?

If you boil again, your bitterness will go up. The problem is bitterness sort of maxes out around 80 IBUs. There are a couple of recent Beersmith podcasts talking about the threshold if you're interested. I don't think you're going to notice a difference in bitterness.

You will probably notice a change in hop flavor. I would take some of the hops planned for dry hopping and throw them in at the end of the reboil. Perhaps, a half ounce of each type with 5 minutes to go and then another half of each at flame out. Then go and order some more hops for dry hopping. You have some time before you need start dry hopping.

DME adjustment:
(Target OG Points - Actual OG Points)/44*Wort Volume= lbs of DME needed to boost OG

i.e.
Target OG: 1.088
Actual OG: 1.075
Wort Volume: 6 gallons
(88-75)/44*6 = 1.8 lbs DME needed

If you haven't boiled the extra bout yet, I wouldn't. Agreed on bumping up with malt extract if you end up with low OG.

If you've already done the extra hour of boil, RDWHAHB. There is enough dry hopping to give you plenty of aroma. Besides, it's an imperial IPA, can you really get TOO much bitterness?