After application from 12.0.6 to 12.2.4 --> Duplicate Indexes

HI,

We have upgraded to 12.2.4 and post golive have certain performance issue for reports. We have found that new indexes have been created but certain indexes are duplicate.

Example :  Old index is named as ASO_QUOTE_HDRS_ALL_N998 and new index created by upgrade is ASO~QUOTE~HDRS~ALL~N998

Logically the old index should have been dropped automatically and new index name should have remained same.

Report might be still using old index and new index or there may be conflict due to which the report performance has degraded across modules.

Kindly help to clarify whether this may be causing performance issues and whether old indexes should be dropped.