To duplicate a record (row), simply right-click on a record and select the Duplicate record option from the dropdown menu.
For another way to duplicate a record, you can also hold down the Alt key while picking up a record from the drag handle on the leftmost side of the record. While you're dragging the record and holding down Alt, a green plus sign should appear. When you drop the record, a copy of the record you dragged will be created at the place where you dropped it.
Currently, it is not possible to duplicate records when using one of our mobile apps. For a more in-depth understanding of the differences between our mobile and desktop offerings check here