When you right-click in the cast list, the menu item "Past And Append Cast" should appear at the bottom. If it doesn't, you can use Excel:

First, copy the entire cast (Open Profile, right-click in the Cast-List), paste it into Excel, and do the same with the second profile, pasting it directly below.
Then, be sure to delete the lines in the middle:

</Actors>
</CastInformation>
<?xml version="1.0" encoding="iso-8859-1"?>
<CastInformation>
<Title>Movie Title</Title>
<Actors>
Then copy the entire list into Excel, go to the new profile, and paste it as "Past All Cast."
You can then sort the profile, insert dividers, etc.
Same with Crew.

Hope that helps