[_TwoFinger]

> having to retype the whole filepath when using mv can lead to errors.

If you use bash, or any readline-based command line (in emacs mode):

  mv long.file.name |^W^Y^Y

results in

  mv long.file.name long.file.name |

(| is the cursor). Then, you just edit the second copy of the filename. BTW, M-C-b/M-C-f will move by one whole "argument" (even if it contains escaped spaces).

edit: and if your filename has spaces, replace the ^W above with M-C-b C-k