Solution or Workaround
SDE for Informix administration commands can use the -D option to select a database in which a layer is stored and retrieved. However, another layer with the same name and owner cannot be created, even if it is to reside in a different Informix database on the same Informix server.
Though the database name is stored correctly in the "f_table_catalog" column of both SDE.LAYERS and SDE.GEOMETRY_COLUMNS, it is not being used to differentiate between layers correctly.
Create same-name tables in different Informix databases using different owner names.
This is a known problem.