I know they *can* do it, it just seems odd to have got it twice.
I Tweeted the guard (some of the guards actually tweet live) and he moved us to another pair of free table seats and gave us free drink vouchers which was pretty decent. He couldn't understand why it had happened.
Very strange. Is there some feature, for example, that allows frequent traveller members to bump people from their favourite seats? Or does the Schengen "portion" vary in size, a bit like if you book economy seats in low-numbered rows on legacy airline flights you're quite likely to lose them as the curtain moves based on business class demand?
An interesting observation on the side - the French staff I encountered were properly moody and seem to think passengers are nothing but trouble (the buffet steward snatched the vouchers off us with a real feeling of Gallic disdain, the one on the way out was similarly abrupt and rude) whereas the English guard was excellent, seeming proud of his train and nothing being too much trouble.
And the e320s are very nice, particularly the seats. In particular I like the way you can extend the seat base out for more underthigh support if you're tall, and the proper high backs, nice and wide too. Not as classy looking as an ICE and a bit rough riding ("typisch Siemens") but otherwise excellent; far, far better than any of the TGV-derived rubbish that Alstom like trotting out.