However, the concept you're describing is often seen in the use of kennings, which are figurative phrases used to refer to something else. While not technically "double metaphors," kennings often combine multiple metaphors or imagery to create a more elaborate and evocative description.
For example, the phrase "whale-road" is a kenning for the "sea," combining the image of a whale and the path it travels. Similarly, "battle-sweat" is a kenning for "blood," using the image of sweat alongside the violence of battle.
So, while a specific term for a "double metaphor" doesn't exist, kennings often employ multiple layers of figurative language, which achieves a similar effect to what you might consider a double metaphor.