URGENT! Radiator Change

[THE_Liam]

Right guys, can't find anything on the search function because my Internet is down (Virgin are shit) so I'm on tapa. Swapping the rad on my early phase 1 XUD for one that Kyle gave me off another phase 1, and there's a problem: The old rad has 2 small pipes going into the bottom of the expansion tank and the new one only has 1. I really don't wanna buy a new rad because this is a temp car and the HG might have gone anyway. What are these pipes for, and is there a way I can bypass one?

Any ideas greatly appreciated