Herb, that didn't work for me -- I had to do two separate purchases of four vouchers in order for two to show up as free. Otherwise it showed one free out of eight added to the basket, each of them the same amount (100 euros).
No big deal, as it was better for me to spread this across two funding sources anyway, being that it wasn't a planned/budgeted expense and I just spent a bundle on high-end ribbon and tube condenser mics. :-)