The Copy & Paste feature is useful for taking one item and putting it on multiple slides without having to perform the search/upload action repeatedly. Unlike the Duplicate feature, where selected items are duplicated once on the current slide, Copy & Paste allows you to paste items on any desired slide.
On creation canvas, select a single item, multiple items or a group and click copy as shown below.
Note - To select multiple items, press control on a Windows computer and command key on a Mac.
Then, go to the desired slide and paste the selected items as shown below.
Additionally, you can also use keyboard shortcuts Ctrl+C & Ctrl+V (or Cmd+C & Cmd+V on a Mac) to perform the above action on selected items.