In the DFW metroplex there are many haunts within a few miles if each other.
Dallas has 3 I can think of within a 10 mile radius. Fort Worth also has 3 within a 10 mile radius as well. Since the population is so large, the close competition does not affect the haunts.
Most haunt go'ers visit more than one haunt a year so it shouldn't matter. Maybe you could partner with the other haunt and co-promote each others event. Maybe even sell a combo ticket that will allow the customer to visit both haunts at a discount.