pot-files

How can I merge 2 .POT files (translation files)

I have the following situation: One product which I want to translate, that has two separate websites, one for admins, one for customers. The codebase is CakePHP. Both sites are completely separate from each other, they are complete CakePHP sites. And they both have A LOT of strings in common. So, with CakePHP I generate the .pot files...