Why copy paste dims gone massive, normally stay size as source

copy pasting some objects and dims out to an new 'page/scene.
they go very big, normally I even use this method to bring in custom dims sizes.

I see it was using milimetre small, so why. I presume I have altered its size and kept it as that name, so when it sees a new file it adopts the size already there for that name ?

I do wish Rhino had a variety of sizes as millimetre small is far from being small.