No multilingual support - VM creates tables in wrong place

[bitstomper]

Hi,

I recently upgraded my Joomla installation and VM 1.1.9 to 2.0.6.
I used tutorial and Jupgrade.
All worked well except I now have 3 sets of tables in my database:
- the new j25_ virtuemart_ tables
- the j25_vm_ tables
- the old jos_virtuemart_ tables

I have installed additional (Dutch) language packs for Joomla and VM.

However if I switch the default front end language to Dutch, VM falls over - modules are not displayed, not products and categories.
I have used the migration tool to 'install and update if necessary' function and discovered it did create new language tables but in jos_virtuemart_ which is my old installation.

Two questions: how do I resolve this?
Can I drop all unnecessary tables and if so, which ones?

PS Joomla plugin language filter is enabled.
Ah, one more thing: if I use url with /nl/ in it the site works fine. Even when front-end is set to English as default. With Dutch as default VM falls over.