File this one away for reference if you are upgrading to R12, or if you are applying some patches, and your Create Accounting program starts giving you ORA-00001 errors. My Oracle Support note "Create Accounting Program Ending In Error:An internal error has occurred in the program xla_je_validation_pkg.populate_segment_values. ORA-00001: unique constraint (XLA.XLA_AE_SEGMENT_VALUES_U1) violated." from document ID 1902705.1 is directly on point with the files, versions, and patch which will resolve this.
If this helps you, please let me know so I can look for more of these types of articles in the future!