Cross Dissolve Two Clips on Different Layers

To cross dissolve between clips on different layers, I place one over the other and move the anchors on *both* clips so that they match the clips' overlap; but this gives a "dark" crossfade (as though a fade in from black is being included in the summing). If instead I move only *one* of the clip's anchors, the cross dissolve looks better and seems to match the result you get when dragging the Cross Dissolve transition over two overlapping clips in the same layer. Which of these two approaches is the correct one? (moving both clips' anchors or only one).

Whichever one gives you the result you want is the right one. There is no right or wrong.

Hi solarama,

By grabbing those clip handles and dragging them, you are creating an opacity transition to zero.
Image looking through the upper track to the track below as the clip becomes transparent.
If you just apply this opacity fade to the top clip, it will work like a standard cross dissolve.

If you add another opacity transition to the clip on the bottom track at the same time, then you are looking through both clips as their opacities change to see through to the emptiness below them, which is displayed as black. That's why you see the transition darken at the mid point.

You can confirm this by switching the view background from black to checkerboard in the Timeline View Options button (just above the timeline timecode when in the Edit page). The checkerboard background helps you see opacity.

Charles is correct. The look you want is the right technique.
If it's just a conventional crossfade you want, then just apply that opacity transition to the upper track.

If you have both clips on the same timeline track, then just right mouse click on the edit point between them and add a cross dissolve effect.