Which type of residence typically consists of two separate dwelling units?

A duplex typically consists of two separate dwelling units that share a common wall, making it a suitable answer to the question. This type of residence is designed to accommodate two families or households, usually with each unit having its own entrance. The configuration allows for more efficient land use and can provide an economical living arrangement for those looking to share a property while maintaining some degree of privacy.

In contrast, a townhouse is generally part of a row of similar units, often with multiple stories and potentially with shared walls but does not exclusively refer to two separate dwelling units. An apartment refers to a unit within a larger building that may house many different tenants, not limited to just two homes. A Victorian house is characterized by its architectural style and historical significance, but it does not inherently denote multiple dwelling units. The focus on the two distinct living spaces makes the duplex the most accurate choice for the question posed.