if u still care..how my teacher tought me is
the effect is opposite to that of magnets for example
If both wires have current going downswards ( pretens its like magnets ) so north and north they are supposed to repel..but no in this case its the oposite they attract
if wires have current in opsite diretecttion..so north and south..they suposed to attract but no in this case its the opsoite they repel
cheers good revision for me :p