On ours you can quantity those. But then they'll check for where the missing voucher is. I don't take risks really, there's no regular customers I like enough to skank sainsbury's for.
The best thing imo is the fact that *take note people* vouchers in sainsbury's are purely a means of taking money off. They don't check to see if you've spent enough, or bought a particular thing. So, when I bought my ultimate pizza the other day, I used two radio times vouchers. £1.50 off that. It helps cus my mum has the discount card for the greater good, so I never see it.
Tell you what though, the pizza was f**kING GORGEOUS!!!!!!!!