Identifying Autopens
This early Aldrin autopen (seen used from 1966 through 1969) is also commonly seen on Apollo 11 crew-signed pieces.
This pattern is seen from mid 1969 and is commonly seen on Apollo 11 first day covers as well as crew portraits.
Another common Aldrin autopen, this one less obvious than the "Edwin" pattern. Seen used through to at least 1979.
This rubber stamp of Aldrin's signature is apparently a relatively modern creation and was not used by NASA or by Aldrin himself.
This topic is discussed in some detail on the Neil Armstrong page. To summarize briefly, during a period following the Apollo 11 mission someone at the Astronaut Office (likely not one of the astronaut secretaries) apparently produced a quantity of fake signatures of the Apollo 11 crew members in response to autograph requests in place of the usual Autopens.
A significant number of these 'secretarials' were Buzz Aldrin signatures, either as part of Apollo 11 crew signed items or on their own, and some examples of this signature style are shown below.