Identical worksheets are needed prior to using the Consolidation feature, creating a sum across worksheets or using the Paste Special Math features to create summary worksheets. By grouping the worksheets first and then adding rows or columns, changing headings and other formatting operations, you ensure that the spreadsheets remain uniform.
In 1986, mimeograph machines were (for the most part) replaced by digital copiers in elementary schools. Those of us teachers who experienced using mimeograph machines will forever remember the distinct smell of the still_damp, purple_ink worksheets that we handed out to our students _ by the ream full. (If you're like me, you can remember that smell right now!)