Bug: Multiple block dragging doesn't always work

[matthewlipski]

In specific cases, dragging and dropping multiple blocks doesn't work for unknown reasons. Two known cases where this occurs include:

1. When two or more selected blocks are the same (same type and content):
   
   Dragging one of the selected blocks will only drag that block, not all of them.
2. When dragging and dropping multiple blocks out of the editor:
   
   Attempting to drag one of same blocks again will only drag that block, not all of them.