if your attempting to Duplicate the sim as in. not just have your phone book
on the other one, But have the other one actually have your info on it to
where u could use it to make phone calls and such, its NOT possible. i tried
everything. Nextel has to activate the simcard.  i actually got as far as to
get my cellular # (areacode and number) into the simcard, BUT getting your
Directconnect # onto the sim is the problem. nextel customer service has to
do that over the air. i tried every type of software i could find online to
do it. but nothin would work.

Now u could always use the Phonebook companion (or whatever its called) to
put your phone book onto the other sim card, then if u ever need to have it
activated  because you lost your other one, then u would have to call nextel
and tell them you need to switch your # over to the new sim, they will do
it, but then the original simcard is blocked, aka.. cant use it.
i hope this made some sense. lol