Не часто работал с DataSet, но судя по http://msdn.microsoft.com/en-us/library/4swwh51k(v=vs.100).aspx, это видимо так и должно быть:
Цитата | ...When merging a new source DataSet into the target, any source rows with a DataRowState value of Unchanged, Modified, or Deleted are matched to target rows with the same primary key values. Source rows with a DataRowState value of Added are matched to new target rows with the same primary key values as the new source rows.
|
Пусть меня поправят, если заблуждаюсь. |