Yes, this is a duplicate of
CONF-32139, but it is because that issue was marked as Resolved because there was a desire not to delete pre-existing indexes.
I think the proper resolution here is to do some checking in the upgrade task to determine if the index already exists and if so, use that index versus creating a new index. I know that SailPoint did this when we had many hundreds of clients running Oracle who added indexes for performance reasons through the Statistics and Query Analyser tools that improved performance in our application. This made the upgrade tasks run smoothly to finish without upsetting the clients who had already added indexes by halting their upgrade tasks.
I would like to have this issue revisited as our largest clients are running Oracle backends and will see this issue in their environments. If we checked for the existence of an index on the table and column that we are about to index and then did not do so if it already exists, then the upgrade experience would be smoother overall.