I am using the rlwrap utility under linux for command line editing while using sql*plus.
Everything is fine except that the utility echoes every command I enter from the keyboar
This was a known bug with pre-0.36 rlwrap in vi mode. You don't mention your rlwrap version and editing mode (i.e. emacs or vi) but I would suggest upgrading to rlwrap-0.37 and filing a bug report with the rlwrap author if that doesn't help