There is a non-obvious two step way to avoid this:
1. With the Move Tool selected, make sure no layer is selected. (A quick way to do this is to tap the escape key.)
2. Press & hold the Alt/Option key & then drag out the marquee.
If you do not do step one, as you probably know you will duplicate & drag the layer if the Alt/Option key is held down. This can be much more annoying than unintentionally dragging the layer because it takes two undos to correct -- one to undo the move (the "transform" step in the history panel) & another to undo the duplicate. It is easy to overlook that, do a single undo, & end up with multiple duplicate layers stacked on top of each other.
The Selecting Objects help topic is not at all clear about this. This is the closest I could find to any mention of using the Alt/Option key for this:
