My data points in Brazil (20+ properties over the years) are the following:
Ibis: only one voucher (good for soft drink, water or low end beer), regardless of number of guests
Mercure: one, sometimes two vouchers (if two guests), good for soft drink, water, low end beer or glass of house wine
Grand Mercure, Novotel & Pullman: two vouchers, also include cocktails (sometimes limited to caipirinha)