I second what Ginny said....
I too had a similar situation when I got my 2.... Trust me, patience is the key...
4 months later, My boy Rebel, who settled immediately is a crazy boy when he's in the house, but his sister Marble who was so shy (and liked to wee on my bed) when she first arrived is really sweet & laid back...(Apart from her obsession with stealing pens and ripping loo roll..!!)
Once they are outside they have a total change of personality though, Marble is a real explorer... Rebel on the hand doesn't like being out so much and is scared of almost everything...
I guess what I'm trying to say is that your 2 will never have the same personality, but they will settle in, and as they get older you will find their true personalities coming out....