Duplicating Lines
To duplicate lines in an open editor file, type the original line
number followed by a colon. When you press Enter, the text of the
original line will be duplicated on the next line number (the
line number increment is determined by the
MAXSTEP command).
For additional lines commands, see:
Adding lines to a file and
Inserting lines.
Example:
100:THIS LINE WILL BE DUPLICATED [Enter]