ISSUE:
Duplicate items appear when viewing items in Datasheet view in SharePoint. This also happens when using the Export to Spreadsheet (Excel). If duplicates appear in Datasheet view, they will also appear during Export to Spreadsheet and vice versa.
DESCRIPTION:
The list has got versioning switched off, and views fine in standard list view. However, when you switch to either datasheet view or Excel Export it shows the same rows up to three times in sequential rows.
WORAROUND/SOLUTION:
The affected lists have a REQUIRED lookup field which allows multiple values.
If you have a view that does NOT include this field and it is either a datasheet or you "Switch to Datasheet" then datasheet shows duplicate items depending on how many multi-values are selected.
Our work-around was to create a specific Datasheet view with the field included. The multi-value field does not show in datasheet, because multi-value lookup fields don't seem to work in datasheet. However, it's important to include the field in the view to avoid duplicates.
Unfortunately, if you have a view that does not include the field and then "Switch to Datasheet" you will encounter the same problem.
The duplicates appear also when you try to Export to Excel. If you have a view that would be affected by the "Switch to Datasheet" duplicates problem, when you try to Export to Excel, it will also appear.
