Clips in the bin (top-left) can be copied. One way is to right-click the clip and COPY. Then, in an open space in the bin, right-click and PASTE CLIP.
Clips on the timeline can be copied by selecting (highlighting) one or more, then pressing <ctrl-C>, to copy them.
Place the scrubber (red line) where the clip is to be inserted and press <ctrl-V>. Choose one of the paste options: insert, overwrite or overlay.