1. u should create:
- database with particular character set, that support both languages (if u have oracle 8.1.6 and less)
- 2 different tablespaces for each language, that support need language
(if u have oracle 8.1.7 and more) and place 2 (or more, as u need tables, that depended from language in different tablespaces)
2. u should tune environment in client boxes, that should use 2 languages.
- NLS_LANG variable (language, territory, charset)