Initially issue comes from Q3.2 ->Q4 data migration for budget@name:
This happens because unique index was introduced for initially non-unique field:
One need to improve migration script to rename duplicates when migrate from non-unique indexes to unique one for budget@name.
1) Common mechanism to migrate non-unique values to unique ones implemented and documented (https://wiki.folio.org/display/FOLIJET/Spike%3A+Investigate+data+migration+strategies)
2) Q3.2 ->Q4 data migration for budget@name fixed