The Split View button found at the right edge of the Power Inspector Toolbar can be used to split the Inspector Drawer into two separate views.
This can be useful for multi-tasking purposes, for example if you want to compare or migrate data between two different targets.

When the Power Inspector view is split, the Split View button is replaced by a Close View button, which can be used to close the view in question.

Shortcut: The keyboard shortcut Ctrl + Space can also be used to split the selected Inspector Drawer – or close the Split View if one is already open.

Peeking

Another way to split the Inspector Drawer is by peeking. The easiest way to peek at an Unity Object is by middle-clicking a GUI element that represents one.
This works with items in the Hierarchy window, the Project window and with Object fields in the Power Inspector window.