If I’ve created 3 layers and three different types of artwork, select
all three, the copy/drag these items, how can I stop Intaglio from
placing all of the newly copied items into the selected layer? At
present, I have to then re-separate these parts back into their layers
again. It’s a pain in the @£$%. Is there another way, or is this yet
another feature request?
That sounds like another feature request to me. Another option might be to drag the one in the active layer, switch layers and repeat the drag (Edit > Repeat) with the object in the new layer, etc.