Duplicating a codeline in ABAP is done via CTRL+D.
Upps, I did that in ABAP in Eclipse: Where is my code? The editor just deleted my code and did not duplicate it. Grggghhhh....
Don't worry. We can help:
Unfortunately the eclipse folks have defined CTRL-D as the delete operation of a code line.Years ago they forgot to ask SAP when they did that fatal decision :shock:
In Eclipse you can duplicate a codeline via the shortcut CTRL+ALT+Up/Down.

Another step successfully done on your way from ABAP workbench towards ABAP in Eclipse.
Have fun.
Thomas.