Casino welcome bonus comes with different condition with different amount and because of the  bonuses some gamblers cheat on the casino bu creating multiple accounts. Though if the casino accept that no pro. But I don't think so. We have seen some situations whereby the gambler was caught and he denied of having multiple accounts or brought out different stories to cover up.
An another thing if a casino is giving bonus, they should make it easy and not complex. There are some casinos that stated first deposit bonus but at the time when you deposit nothing comes out.