[Weekly Snapshot] An ISIN may appear more than once in a single snapshot file

[AnnaDSBTechnicalSupport]

Issue:
Currently when using Weekly Snapshot service, an ISIN may appear more than once in a single snapshot file.

Impact:
When downloading a single snapshot file on the Weekly Snapshot service may have duplicate ISINs.

Workaround:
DSB will deploy a change to fix the issue.