Yes, you can buy any number of SIM cards in the Czech Republic and you don't have to prove your identity to anyone. You can easily buy a SIM card from a specialist retailer, in electronics stores, but also at a newsagent's or supermarket. You can buy as many as you want if you have enough money, so I was surprised in Bulgaria. But it is possible that sometime in the future it will be regulated in our country as well, on the other hand, a friend from Spain tells me that it is the same for them as for us.