You’re absolutely right. Pasting creates an exact copy of the component/block/article/page you choose but then that copy stands alone and if you change that new instance of it it only changes in the place you edit, not in the original place.
this terrified me slightly as was convinced I had overwritten past pages. works so really well to use for generic headings and endings e.g. Objectives and Summary. keep the titles the same but then just change the body.