2 MKV's to 1 File

[apdso9]

I have a Bluray (Slumdog Millionaire)
The Bluray have 4 Titles. I want to Rip The title with the English soundstreams and the the Title with the German streams.
How to make this?
I tried to rip it . But if I choose 2 Titles I will get 2 MKV's.
When I load the 2 rips in MKVtoolnix then I get an errormessage "Title 3 is alredy in the target file"
How to create a proper MKV from 2 MKV's.
Somebody here who did this already?

[twa000]

Just curious - the German version I have has 4 titles, but 3 have German and English audio tracks (although all have different audio and sub title set up)so I assuming that you are trying to put together one MKV with both German and English DTS 3/2 audio tracks - For German and English audio, it is the first time I have seen the main title language in DTS 3/2+1 and the other in DTS 2/0.
Afraid I kept the DTS 3/2 German audio plus English 2/0, although we normally listen to the English