This macroscript lets you select a spline and generate one or more splines with a specified offset. Unlike the 3DS MAX offset function in 'Editable Spline' - this offset spline detached from the original spline.
Check the 'consecutive' checkbox to keep the result selected.
To use it - go to Maxscript / Run Script and pick this file. You will find it in the 'rdg::preset' category of Customize -> Customize User Interface . and you'll be able to assign the script to a quadmenu - shortcut key - etc.
Look for the script titled 'generates a new offset spline'.
Assign a shortcut and voila - you're done!