Question

If you open more than one swatch library from the window>swatch libraries menu, each library opens as a new panel, grouped by default with other open swatch libraries.

Answer 1

Question : What is a swatch library

Explanation: Swatches are named colors, tints, gradients, and patterns. The swatches associated with a document appear in the Swatches panel. Swatches can appear individually or in groups.

You can open libraries of swatches from other Illustrator documents and various color systems. Swatch libraries appear in separate panels and are not saved with the document