You might be inclined to put the couple's combined name into the profile's first and last name, but doing this will lead to a lot of confusion. As a result, you'll for sure have odd looking salutations in letters and emails. Plus, if the couple separates, their giving history will be gone from your database and dealing with gifts will be a pain.
When a couple donates, each person should have their own profile in your database. You can then create a "Combined Giver" general relationship between the two individual accounts, and Andar will automatically show their combined gift! You can even use a unique combined giver name and salutation to address letters correctly. Plus, Andar gives you the option to address individuals separately or combined. You can even join an entire family together if you want.