Dual source mapping occurs when logical facts are shared by both Transactional Business Intelligence and Oracle BI Applications. Subject area sharing and dual source mapping are relevant for query re-direction. For example, you can have a logical fact, Fact - Project Cost which is used by both Transactional Business Intelligence and Oracle BI Applications. However, the subject area, Project Costing - Actual Costs Real Time is used only by Transactional Business Intelligence. For more information, see the Oracle Fusion Middleware Metadata Repository Builder's Guide for Oracle Business Intelligence Enterprise Edition, 11g Release 1 (11.1.1).