I found a solution myself. First of all, I created a SQL Query in DB, which adds a row and return a Num value of new row:
INSERT INTO [Table] ([Name], [Photo]) VALUES (@Name, @Photo);
SELECT @@IDENTITY
I called it "InsertAndReturnIdentificator". And then I used inserting (with this new query) and deleting rows in adapter directly, without using a DataSet
private Nullable<decimal> row1;
private Nullable<decimal> row2;
row1 = adapter.InsertAndReturtIdentificator("Name1", File.ReadAllBytes(@"Images\Photo1.jpg")) as Nullable<decimal>;
row2 = adapter.InsertAndReturtIdentificator("Name2", File.ReadAllBytes(@"Images\Photo2.jpg")) as Nullable<decimal>;
... performing test ...
adapter.Delete(Decimal.ToInt32(row1.Value));
adapter.Delete(Decimal.ToInt32(row2.Value));