As per One Piece logic, a person cannot have 2 Devil Fruit powers. The Yomi Yomi no Mi fruit revives the one who eats it. The powers of this fruit are a one-time use, and has been used up after Brook was revived. Can Brook now have another Devil Fruit?
Yomi Yomi no Mi's ability to revive its eater is just the tip of the iceberg. Brook thought it was the only purpose before the timeskip. However, after the timeskip, he reveals that he has now learnt the true power of his Devil Fruit.
The soul of a human who dies normally goes to the land of the dead, but his Devil's Fruit emits a powerful energy that allows his soul to remain in the living world. During the 2 years of training, he has also mastered its other abilities, such as:
- Letting his soul leave and enter his body/skeleton at will
- "Pouring his soul" into his music to show illusions to people
- Summoning cold flames from the underworld
- Surviving damage that would otherwise be fatal (he cannot be seriously injured unless his bones are hurt)
Long story short, Yomi Yomi no Mi is not a "one time use". Brook cannot have another Devil Fruit, unless Oda-sensei's hyper-creative imagination provides him a loophole.