"Double complementary" is not a standard term in any field, so it's difficult to provide a definitive answer without more context. However, based on the word "complementary," it's likely referring to a situation where two things are complementary in two different ways.

Here are some possible interpretations:

1. Complementary in two separate aspects:

* Example: Two colors might be complementary in terms of their placement on the color wheel (like blue and orange), but they could also be complementary in terms of their emotional impact (one calming, the other energizing).

2. Complementary in a combined effect:

* Example: Two ingredients might be complementary in taste on their own, but when combined, they create a new flavor that is more than the sum of its parts.

3. Complementary in a cyclical or iterative process:

* Example: In a design process, two phases might be complementary in that the output of one informs the input of the other. This could happen twice, creating a "double complementary" cycle.

To understand the specific meaning of "double complementary" in your context, please provide more information:

* What is the subject matter? (e.g., colors, flavors, design, etc.)

* What is the context? (e.g., a book, a presentation, a conversation, etc.)

With more context, I can give you a more accurate and helpful explanation.