How have people stopped the GroupWise driver from creating a duplicate
Internet Email address?

Groupwise is setup to build the address GIVENNAME.LASTNAME@company.com

BUT, if there are more then one SALLY SMITHS the driver will still
create the Groupwise account but now groupwise has 2
SALLY.SMITHS@company.com

And if I understand it correctly the Internet Email gets generated by
GroupWise are account creation time.

I'm a little lost and any help would be appreciated.

Thanks