All right, I found a solution:
FileStream inf = new FileStream("path1", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
FileStream outf = new FileStream("path2", FileMode.Create);
int a;
while ((a = inf.ReadByte()) != -1)
{
outf.WriteByte((byte)a);
}
inf.Close();
inf.Dispose();
outf.Close();
outf.Dispose();