I'm not sure exactly what you are describing but if you have accidentally copy/pasted a table, you can select it and delete it. It is that simple. Which one to delete, the original or the accidental copy, is a decision you will have to make. If there are any formulas in other tables that rely on the data in the original table, it is probably best to keep it and delete the duplicate. You said you added new data to the duplicate so you should copy/paste or type that data into the original table first if you want to delete the duplicate. However, if no formulas rely on the original table, maybe it would be easier to delete it and use the duplicate from here on.