old orders not visible but present, order numbering restarted leading to problem

[Lexiboy]

After updating from Joomla VM 2.6 to VM 3.2 I have the following problem.

The layout of the order numbers changed and Virtuemart started with order 1 again.

Old VM:

750f03432
354003433 (last order, 3433)


New VM:

YMRV011 (first order listen after update, number 11)
BSY2012
etc

The problem is that the
1) old orders are not visible anymore in VM order list.
2) apparantly this leads that old and new orders now get combined. So new order 11 is merged with old order 11. And this leads to products added to the order that were not ordered, and old payment and shipments included.

This occors after the order was placed, so checkout is correct. But order notifications are wrong, and the orders are also incorrect when opened in back-end.

How can I fix this?