Darden testing combined Olive Garden and Red Lobster concept

The parent company of restaurant-chain powerhouses Olive Garden and Red Lobster is testing a new restaurant format that would combine its two best-known brands into one building, allowing for expansion into markets once considered too small for a standalone location.

Darden Restaurants Inc. will open its first "synergy restaurant" in March in Palm Coast, Fla., and expects to open two more locations in the next year.

The company is trying to avoid some of the pitfalls that have held back dual-brand fast-food restaurants. A big one: Blending the brands too much by using common menus and sharing dining rooms, diluting what diners enjoy about a particular brand.

"We've developed a prototype that maintains the integrity of all key brand touch points including separate front doors, separate lobbies, separate bars, separate dining rooms and brand-specific menus," chief operating officer Andrew Madsen said during an investor-day presentation in Orlando Feb. 1. "The primary areas of capital synergy including a shared kitchen, shared refrigeration and shared storage are invisible to the guest."