Spatial :: ORACLE 11g Spatial And GRS 80

I am working on a project that will require both projected coordinates and geographic coordinates for different product files coming in. I have no issues defining, storing, extracting or matching the geographic coordinates. My columns for those coordinates with SRID 8307 are defined in the user_sdo_geom_metadata table as follows:

INSERT INTO
USER_SDO_GEOM_METADATA (TABLE_NAME, COLUMN_NAME, DIMINFO, SRID)
VALUES
('INVENTORYGEOMETRY','INVGEO',MDSYS.SDO_DIM_ARRAY(MDSYS.SDO_DIM_ELEMENT('Longitude', -180, 180, .05),MDSYS.SDO_DIM_ELEMENT('Latitude', -90, 90, .05)),8307);

the index: create index "MYDB"."INVGEO_IDX" on "MYDB"."INVENTORYGEOMETRY"("INVGEO") indextype is MDSYS.SPATIAL_INDEX;

how I am going to have a column that has both Geographic and Projected coordinates. Am I allowed to define more SDO_DIM_ELEMENT(s) fro the SDO_DIM_ARRAY with different min/max values. As an example, would I be able to still use an SRID of 8307 for both WGS 84 and GRS80 data (ellipsoid), something like the following:

INSERT INTO
USER_SDO_GEOM_METADATA (TABLE_NAME, COLUMN_NAME, DIMINFO, SRID)
VALUES
('INVENTORYGEOMETRY','INVGEO',MDSYS.SDO_DIM_ARRAY(MDSYS.SDO_DIM_ELEMENT('Longitude', -180, 180, .05),MDSYS.SDO_DIM_ELEMENT('Latitude', -90, 90, .05),
(MDSYS.SDO_DIM_ELEMENT('FIXEDGRID_.5Resolution', 0, 26916, .5)),8307);

Is that possible or do i have to create a new column in the database? Also, I don't know the relationship between the SDO_ELLIPSOIDS table and the SDO_GEOMETRY table.

how I'm going to make this work for both the geographic and projected coordinates or if I'm going to be able to make it work.