What TKU are you using? Why do you think it is a duplicate?

It is really hard to tell with no details about what appears on the SIs.

It is possible to run more than one PosrgreSQL on a machine.

Look at the age_count for each.  If one is negative, it will eventually age out. There could be any number of reasons as to why Discovery found enough different from scan to scan to make a new SI and start aging the os SI.  Could have been a key change or better discovery after a recent TKU has been applied

Either you will need to talk to support and provide record data for an example or you are going to have to provide more details on the forum.

If this is on Unix what postmaster and postgres process do you have. For Windows pg_ctl and postgres processes.

So, it does appear that recent updates to TKU changed the Postgres SI enough to generate a new SI or a properly authorized credential was deployed that collected better information for Postgres and Discovery just made a new SI (key change) because it was different enough from the older SI to warrant the new SI.

Please scan those Postgres providing hosts again.  If the Postgres SI positive age_count increments by the same number as the Postgres SI negative age_count decrements, this is basic confirmation of a key change.

You have 2 options here.

Simply wait for the older (negative age_count) SI's to be destroyed based on aging criteria,

Manually destroy all the older (negative age_count) Postgres SI's to remove them from your displays in the UI and reports

hth

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