You can specify that duplicate (non-unique) member names and aliases are allowed in a database outline, with some restrictions. For example, a database may require two members named New York in the outline, one under a State member and one under a City member. In the outline, the member names are both displayed as New York. The qualified member names are:
[State].[New York] [City].[New York]
You can view the qualified member name for a duplicate member in the Member Properties dialog box in Outline Viewer. When inserting duplicate member names in scripts, partition definitions, and so forth, the qualified member name is inserted for you.
Dimension names, generation names, and level names must always be unique, and siblings under a parent member must always be unique. For a list of restrictions for duplicate member names in outlines, see the Oracle Essbase Database Administrator's Guide.
Within a duplicate member name outline, you can tag dimensions (and generations and levels within a dimension) as unique to require that member names for a particular set of members are unique. These tags enable you to specify member name uniqueness at a more granular level in a duplicate member name outline.
For information about duplicate member names, see the Oracle Essbase Database Administrator's Guide.
“Creating and Working with Duplicate Member Outlines” in the Oracle Essbase Database Administrator's Guide