Hello Peter,
Currently, the Spreadsheet does not allow to keep the target formatting options on paste. Nevertheless, as Marc has suggested, the override of the
kendo.spreadsheet.Clipboard.prototype.paste() method would allow you to alter this behavior of the widget in most cases.
Here you will find a small sample which demonstrates how the above suggestion would handle to cell formatting too. Keep in mind however, that this would not cover all scenarios. For example, it won't behave as expected, when pasting text values on cells with number formatting.
Note also, that the discussed functionality
has already been requested on our Feedback portal. Therefore, I would suggest you to cast your vote for this feature request.
Regards,
Veselin Tsvetanov
Progress Telerik