I believe the board rules are clear, you probably cannot stamp the original report. As you can see from the attached rules below for Arizona, it is clear that the registrant or his employee must have prepared a document that is being sealed.
Arizona:
A registrant shall place a permanently legible imprint of the registrant's seal and signature on the following:
... Either the cover, title, index, or table of contents page, or first sheet of any report, specification, or other professional document prepared by a registrant or the registrant's bona fide employee;
The signature line of any letter or other professional document prepared by a registrant, or the registrant's bona fide employee...
California:
(g) (1) All professional engineering plans, specifications, reports, or documents (hereinafter referred to as “documents”) shall be signed and sealed in accordance with the requirements of the Professional Engineers Act and any other laws related to the practice of professional engineering and shall be signed and sealed in a manner such that all work can be clearly attributed to the licensee(s) in responsible charge of the work.