Does "I do, I do" here mean "I will help" or does mean "I love old things"?

Does “I do, I do” here mean “I will help” or does it mean “I love old things”?

“You may well ask why I say them at all. But I have two reasons. Firstly, because my old heart has carried these secret memories so long that it aches with them and would burst if I did not whisper them to you. But secondly, for this: that when you become King you may help us, for I know that you also, Telmarine though you are, love the Old Things.”
I do, I do,” said Caspian. “But how can I help?”


Yes, yes, I do love the old things.


The words in bold: “You also love the Old Things.” - I do = I love = I love Old Things.