It reall would depend on what exactly your policy covers you for. For instance, does it cover landscaping?
When it comes to building, the price of a new home rarely reflects the actual cost. When you go to those display homes centres, the cost of building the new home often does not cover the exterior landscaping, driveways or even some of the features found on the inside. So if your insurance policy is for the rebuild of the actual structure only, then yes it would cost more to “complete” your complex to original should the unthinkable happen and the building was damaged to the extent you would need a rebuild.
The $500,000 more that your building is covered for is $125,000 per unit. It sometimes pays to look at extra costs by dividing by the number of units and see whether that cost is justified in that way. Check out your policy first and see what is covered.