[Scribus] Better quality PDF or catenate them?

[Eilert]

As I explained earlier, importing of PDF pages into a picture frame in 
Scribus turned out rather ugly. Either I'm doing something wrong or 
Scribus just imports them so. So I'd be happy about any comments.

Another idea was to make single PDFs and catenate them. Is there a tool 
which could achieve this? What I need seems rather simple: take a pdf 
with page 1 and another with page 2 and glue them together to make it a 
2-page pdf.

Rolf