For something physical, specially something run by the government, you can ask people during account creation for some identification like full name + date of birth, not allow duplicate accounts to enter the same raffle, and check the id of the winners when they get there (so you don't have companies creating bots).

Harder to game, if desired enough people will still game it by buying entries for others

Grand Canyon’s river lottery doesn’t use recreation.gov and has measures to prevent multi accounters including lifetime bans (which have been enforced) if you apply with multiple accounts in the same lottery.

I was answering to a comment any collectibles. There multi-accounting is rampant and little can be done about it. When it comes to non-physical goods then a lot more can be done about enforcement.