I thought this wasn't supposed to be possible, but I am getting Dragon Souls on my second visit to dragon lairs. It's incredibly useful, as I'm trying to max out a lot of shouts early game.
Has this happened to anyone else?
Also, Dragon lairs are great for multi-tasking. Boss chess + soul + dragon bones/scales. Nice. --- "You don't have to burn books to destroy a culture. Just get people to stop reading them." - Ray Bradbury
When the dragon changes type--dragon to blood dragon as an example--you can get a new soul from them. When they respawn as the same type, most of the time they will not yield a second soul. --- Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn.