Yes, two people could have the same
It is widely known that each Devil Fruit is unique and, as long as its user is alive, there cannot exist another with the same ability in the world.
Can Luffy take second devil fruits or not? No. At present the only person who has, somehow, managed to acquire two devils fruit powers is Blackbeard, and no one knows how he did that. Normally if someone eats a second devils fruit, it'll poison them and they'll die.
The Cerberus Theory - Blackbeard Already Ate a Devil Fruit
Theorists believe that, like the mythical Cerberus' three heads with independent thought, Teach is able to use more than one Devil Fruit. The justification for this theory mainly comes from how Blackbeard and his actions tend to revolve around the number three.
It is well known if a devil fruit user eats another devil fruit they will die(with exception). And, It seems to be possible to obtain a devil fruit by eating its user (Big Mom did this).
No. The devil fruit will lose its powers once a part, even the slightest part of that fruit was eaten by someone.
Actually not just 1, he can eat 3 devil fruits. Yes.
Zoro set out on his journey to becoming the greatest swordsman in the world by defeating Dracule Mihawk, the man who currently sits on the stone. Over the years, he has come a long way and become one of the strongest pirates on the seas. Zoro has attained terrific strength, but he does not rely on a Devil Fruit at all.
With his Awakened Devil Fruit as well as his Haki, which has been advanced in all three spheres, Luffy possesses the power to beat Blackbeard.
The Mizu Mizu no Mi (lit Water Water Fruit) is a Logia-type Devil Fruit that allows the user to control and become liquid water.
Luffy's rubber attributes are a result of him eating a devil fruit called the Gum-Gum Fruit Granting him a rubber-like body, his powers make him immune to electric attacks and most blunt forces, but he is susceptible to attacks made with a sharp object or weapon (eg. sword, spear).
Magu Magu no Mi. Admiral Akainu's devil fruit Magu Magu no Mi is the ultimate weapon for absolute destruction. It is the most powerful raw power (even better than fire) in the One Piece world. This devil fruit allows the user to create and control magma at their will, along with turning themselves into magma.
Mythical Zoans are the rarest type of Devil Fruit, even more so than Logias. Artificial - Artificially created Zoan Fruits that cause the user to permanently take on an animal characteristic; though, much more rarely, the user becomes able to transform at will.
All Devil Fruit eaters lose their ability to swim after consuming the Devil Fruit. It's not just a loss of muscle memory; entering a body of water saps them of all energy. Even entering a bath can drain a Devil Fruit eater of energy and prevent them from using their abilities.
Blackbeard is the only character in One Piece with two Devil Fruits. How did he do it? Marshall D. Teach, better known by his epithet, is arguably the most dangerous living pirate in One Piece.
The circumstances surrounding Zoro's left eye aren't a complete mystery; at the very least fans know that it happened sometime during the two-year time skip. During this time, each member of the Straw Hat crew committed to training and growing stronger.
The Daishou Daishou no Mi is a Paramecia type Devil Fruit eaten by Nefertari Vivi a month after the Straw Hats departed from Arabasta.
She ate the Love-Love Fruit, which allows her to turn her opponents into stone. In order for this power to work, the target must first have feelings of attraction towards the user. Nami is beautiful, and it has been shown that many characters find her attractive, just like Hancock.
This allows him to eat 2 fruits.
Sanji hated Absalom even more because he ate the Suke Suke no Mi. However, though this was the only Devil Fruit that Sanji was ever interested in, he lost interest in the fruit after his fight with Absalom, deciding that he shall just have to peek on women anyway without it.
Enma is the strongest sword possessed by Zoro of the Straw Hat Pirates right now.
One Piece shows a new awakening of a Zoan-type Devil Fruit, confirming that Luffy's version of this rare and powerful ability is absolutely unique.
With the Pika Pika no Mi, Sanji's Powers would grow even further and make him the fastest man alive. Furthermore, this would also make his kicks more dangerous than ever before. Sanji would be able to kick at the speed of light and that would mean his kicks become deadly.
During Sanji's cooking battle in a Loguetown Arc filler episode, it was mentioned that some fish species that should not exist in the East Blue were found due to ocean currents, which made Sanji certain that the All Blue exists.