We had just requested a clone and the behavior of Preserve Data (specially for ecc_agent table) wasn't quite what I expected. So what I understood was wrong, for your scenario e.g. to keep ONLY records in target instance both preserve data and exclude table needed to be defined as well as when request a clone  "Exclude audit and log data" and "Exclude large attachment data" needs to be checked as True.

Here is explanation from Data Preservation

If you set a data preserver on a table where the source instance has more records than the target instance, the data preserved on the target instance also includes the additional records from the source instance.
For example, assume that the data preserver is already in place.

• In the source instance, the sys_temp table contains 100 records.
• In the target instance, the sys_temp table contains 20 records.

After the clone, the sys_temp table in the target instance contains 100 records.

• The 20 records in the target sys_temp table are preserved successfully (per the data preserver specification).
• The source sys_temp table brings over the remaining 80 records to the target sys_temp table./li>

To resolve this issue and to preserve only the records in the target table, create an exclude table record for the target table, in addition to setting the data preserver on the source table.

And here is the KB states that "Exclude audit and log data" and "Exclude large attachment data" needs to be checked as True.