When users or groups share a record, they appear a varying number of times in the sharing pages
|Knowledge Article Number||000233569|
|Description||When a record is shared with a user for different reasons, the user doesn’t appear once for each reason on the sharing pages.|
Sharing a record with users gives them access to that record. You can see who has access to a record, such as an account or an opportunity, on the Sharing Detail page and the Reasons for Access page.To view the Sharing Detail page, open the account or opportunity record and click Sharing. To view the Reasons for Access page, from the Sharing Detail page, click Expand List and then click the Why link next to the user.
On these pages, you typically see a user listed once for each sharing reason. For example, if a user is the owner of an account, you see that user listed on the sharing pages with a reason of Owner.
The Sharing Detail page shows Nina twice: once for each of the reasons.
Now click the Add button and manually share the account with Nina. Give her Read/Write access to the account and associated opportunities and cases. After you click Save, you might expect Nina to be listed three times on the Sharing Detail page. But you see her still listed only twice with these two reasons:
The sharing record with the Associated record owner or sharing reason was combined with the sharing record that has the Manual Sharing reason. Because the manual sharing record has a higher level of access, it appears on the sharing page.
You also see this behavior in API version 37.0 and later in the sharing objects like AccountShare and OpportunityShare.