Simple fix: buy a specific item e.g. a [copy/no trans] necklace and get a random [no copy/trans] reward/gift with it.
Basically the gacha script just needs a small tweek. And of course the rewards/gifts are listed next to the necklace. And one ends up buying 5 times the same "necklace".
Just like in RL: buy a shampoo and get a random item from their product line as gift. Which definitely is not gambling, but comon practice.