Bookmarks have to be unique, but you can reproduce the content of a bookmark
using REF fields as often as you wish. If you set the information from the
first form field, check its 'calculate on exit' property - the REF field(s)
will be populated by the same information.

Probably for the same reason that you can't have two pieces of text
bookmarked with the same bookmark name. At any one time, a given bookmark
only marks one area of a document. Even if you have multiple { SET
mybookmark } fields in a document, the boomark will correcspond to the last
SET field to be executed.

I doubt it. Even if you save a .doc as .rtf and edit the plain text to give
two form fields the same name, Word just blanks one of them out when you
open the .rtf.

Maybe you have the wrong expectation of what a bookmark will do for you -
but if you can tell us what you are trying to achieve, maybe we can suggest
an alternative.