A more thorough explanation:

Droit-droit (drwah-drwah) is a legal term that refers to the unification of the right of possession with the right of property. It is also known as jus duplicatum or dreit dreit. This means that a person has a complete title to lands, tenements, and hereditaments when they have both the right of possession and the right of property. According to the law, no title is completely good unless these two rights are joined together. When the actual possession is also united with the double right, then the title is completely legal.

For example, if John owns a piece of land and has the right to possess it, he has a single right. However, if John also has the right of property, meaning he has legal ownership of the land, then he has a double right or droit-droit. This means that John has a complete title to the land and his ownership is legally recognized.

Another example is if Sarah inherits a house from her parents. She has the right of possession because she is living in the house, but she does not have the right of property until the house is legally transferred to her name. Once the transfer is complete, Sarah has both the right of possession and the right of property, giving her a double right or droit-droit to the house.

These examples illustrate how the unification of the right of possession with the right of property creates a complete and legally recognized title to a property.