The standard Membership provider expects to only keep things in the standard database - if you want to copy the id into a separate database then you have two choices:
1) Add code to the Create User page that the wizard uses.
2) Provide a
custom Membership provider[
^] and do all the database stuff yourself.
Personally, I would go for the second option, as maintaining two separate databases with the same info in synch is more trouble than it is worth.
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