Currently does that mean when it actually gets realised (and assuming there is no clever indexing going on further down the stack, so lets talk PP) that the data will be loaded twice and then indexed, or is there some smartness in the sharing of the LazyArray?

To add clarity to my question, I'm essentially asking, if I've got a Mosaic with multiple copies of same virtual array (perhaps subsetted) does biggus play clever and only realise it once and index many times?