English to French Bus/Financial Printing & Publishing business correspondence

sorry all...
another snag.
Still with this invoice:

at the top, there is the VAT registration number.

Then the table with the job number, the goods amount, the VAT rate and the VAT amount.

Then all the totals at the bottom.

AND THEN, in smaller print (of course) some legal stuff (right reserved to charge interest, goods are property of seller until paiement received, yadiyadiyada) and directly below THAT: REGISTRATION, followed by a number (different from the VAT number).

What???? Am I missing something?
Or is one, the client's VAT number and the other, the seller's? Does that make any sense?

Merci, merci!! :-))