To copy a region, make sure you are in object mouse mode. Move the mouse pointer into the region and left-drag. Ardour creates a new region and follows the mouse pointer as it moves. See Move Regions for more details on moving the copied region.
To copy multiple regions, select them before copying. Then left-drag one of the selected regions. All the regions will be copied and as they move. The copied regions will keep their positions relative to each other.
If you want to copy region(s) to other track(s) but keep the copies at the exact position on the timeline as the originals, simply use Middle-drag instead.