No Title
You CAN copy it. The I-90 form (Application to Replace Permanent Resident Card) instruction has the following blurb (read the bold part in 2nd paragarph):
submit a copy if you have one. If you do not have a copy, and are at least 18 years old, you must file your application with a copy of an identity document, such as a driver\'s license, passport or a copy of another document containing your name, date of birth, photograph and signature.
--//>>
That makes copying of card definitely LEGAL!!!