Action macros you record with the ACTRECORD command can be assigned any name you choose except for the names of AutoCAD internal commands. Macros are then stored to the individual files myMACRONAME.ACTM in the default folder c:\Documents and Settings\username\Application Data\Autodesk\AutoCAD 2009\R17.2\enu\Support\Actions.
AutoCAD scans this folder after you launch a session and loads any ACTM macros it finds here. You cannot name your macro after an internal command name and AutoCAD even refuses to load an ACTM file which was renamed manually.
But be careful - this protection applies only to the names of AutoCAD commands, not to any external (user-defined) commands you may have defined in your LISP applications (defun c:CMDNAME), other add-on programming tool or even a PGP command alias. You can effectively map out (disable, hide, overlay) your existing commands when you inadverently assign a "wrong" name to your action macro. Your commands, menus, scripts and LISP utilities may suddenly and magically cease to work!
Command/macros can be also overlaid in the opposite way - if you name an action macro the same as an AutoCAD localized command name (it allows you to do this), such macro will run the original command, not the recorded actions.