How big?

it's not just building a blank space in the middle; they might have to make the existing opening wider and you can't do that unless the garage itself is wide enough. The header beam also might have to be replaced, and that could mean re-framing the whole face of the garage.

If you have a 16 foot door allowance, dividing it up leaves you with two doors about 7 feet wide. An 18 foot opening can get two 8 foot doors, still kinda narrow to drive through without someone goofing up somehow and whacking off a mirror eventually.

When you use one door you use more than 50% of the space going in and out as two cars won't do that simultaneously. The two doors need a dead space between them and it will take up maybe a foot and a half minimum.

When you have 2 single doors there is usually a raised concrete stem wall in between the two doors to keep the bottom framing plate from being constantly wet from snow/rain that collects on your vehicle and then drips when you drive in the garage.
Hard to say if it will be an easy fix without knowing more details but if I paid for 2 doors I would want them regardless.

Thanks for the responses. I forgot to mention that they have already installed the one big door. The roofing guy was there. He said "that was a big mistake". He also said they may be able to correct it. I emailed the realtor and she is contacting the builder.

What does your contract say and what do your building plans show?

I'll second what was said about the overall width of the garage. Make sure it's not too narrow now.

If you don't absolutely hate it, perhaps you could upgrade something else for the cost it would be to replace.

If your blueprints and your contract say two doors and you wanted two doors, you should complain -- politely but with conviction.

Regardless, at this stage, I suspect you're more likely to get money back than to get the doors you actually wanted -- or you might be able to get a credit or an upgrade towards something else.

Personally, I'd rather have the one big door. It's more versatile -- you can move big items in and out more easily, and if you ever needed to have a handicapped van in the garage, you'd be better off with the one big door. However, that's my opinion -- and we're talking about your money and your house.

I agree and actually switched from two doors to one big door for one of our garages. More versatile. I also agree its your house and your money.

Pick your battles. The single door works better than two. Use the leverage to get something else that you want.