After merge contacts, we activated duplicate contact, the old Audit History record modified in CRM

Hi All,

We are using Dynamics CRM on-premise.
We did 2 steps:

1)We merged 2 contacts. After merge, the following fields were changed in duplicate contact (info from Audit History at 09:40):

09:40
- Master ID ->  empty to master contact
- Merged ->  No to Yes
- Status -> Active to Inactive



2) We activated the same duplicate contact at 09:47. What we see in the Audit History that the old Audit History from 09:40 were modified:

09:40
- Master ID ->  empty to empty
- Merged ->  No to No



If someone has a logical explanation why the old Audit History were modified please share your answer.
Any inputs will be highly appreciated.