Replied 8 September 2017, 3:03 pm EST
I was not able to reproduce the issue at my end related to the copy paste of the date values, with the latest version of Spread i.e Spread.Net6 v6.0.xx06. If no format is explicitly set for DateTimeCellType then it would use the regional settings to set the DateTimeFormat in the cell. In case you are looking for self corrected value then I would suggest you to define a user defined format for the DateTimeCellTYpe, so that the input dtae is formatted in the desired format. Here is the code snippet to achieve the format defined above:
FarPoint.Win.Spread.CellType.DateTimeCellType dct = new FarPoint.Win.Spread.CellType.DateTimeCellType();
dct.UserDefinedFormat = "MM/dd/yyyy";
dct.DateTimeFormat = FarPoint.Win.Spread.CellType.DateTimeFormat.UserDefined;
fpSpread1.Sheets.Columns.CellType = dct;
Hope it will help you. Please let me know if you have any queries further.