Bug in Virtuemart 2.0.6 and 2.0.7b (even on Virtuemart 2 own example page)

[maketheweb]

On both my website and the Example website of Virtuemart 2 I encounter a strange problem with custom fields.
For some reason, the price of the first custom field is always added to the normal price, regardless of the choice of the customer...

Anyone else encountered this problem? I checked it on 3 different browsers (Mozilla, Chrome, Safari)

My own website uses J! 1.5.26 and VM 2.0.7b