When a couple thinks they agree on all issues, it may seem logical to save money and use one attorney to "handle the paperwork." This is almost uniformly a bad idea and can have potentially disastrous effects.
Most lawyers recognize the possibility of conflicts of interest, a situation in which it is impossible to represent both sides fairly. However, some states allow a lawyer to represent clients with opposing interests if the lawyer has informed both clients of the conflict in writing and the clients have agreed in writing to the dual representation. When an attorney does represent both sides, it may open the door to malpractice claims if you were harmed by the lawyer's dual representation.
If you believe your interests were harmed by an attorney's conflict of interest, consult with an experienced legal malpractice attorney right away.