For example, I have a blueprint of a loading station, stop, loading platforms, some belts near it. I want to add a new stop to an existing rail road. I can't paste it on top of a simple rail. Even with shift key pressed.
This behavior is very different from pasting building-level blueprints. They overwrite existing belts with no conflict indication, and with shift pressed, they even overwrite a rotator to belt and vice versa.