Legal Question in Landlord & Tenant Law in Maryland

No one should sign another person's name to a binding contract unless they have a power of attorney to do so. If the other side told one tenant to sign for both that would raise questions of the contract's validity. (It isn't clear from your post who told the other person to sign - if you told her to sign your name that could have a different outcome).

In some cases a person MAY be held to something by accepting the benefit even if they didn't sign an agreement and oral agreements may be binding.

You're encouraged to seek legal advice. While I hope this general legal information helps it doesn't substitute for getting personalized legal advice.