The seven horcruxes in Harry Potter are: the diary of Tom Riddle, the ring of Marvolo Gunter, the locket of Slytherin, the Hufflepuff Grail, Ravenclaw's lost crown, Nagini and Harry Potter.

Voldemort's soul has been split seven times, with eight soul fragments, six made into horcruxes, one in Harry and one in Voldemort himself.

When Voldemort killed Harry, Avada's death curse bounced back under the protection of his blood relatives, and his soul fragments were shattered into two pieces, one of which was attached to Harry's body, and the other was left in the body and later used for rebirth.

Because Voldemort took Harry's blood when he was resurrected, the protection of blood relatives (sacrificial spell) still exists and has not been destroyed (that is, Harry himself is not dead), but Voldemort's soul fragments in his body have been destroyed.

The method of making horcruxes:

If you want to make horcruxes, you must first split dark wizard's soul. Dark wizard split his soul through murder and other evil things. By using a special spell, the soul will be separated and transferred to that object, thus making a horcrux. Let's make it clear here that Voldemort did split his soul through meaningful and deliberate murder, but it doesn't mean that dark wizard split his soul once after a murder.

Because murder is a common occurrence for dark wizard. So, theoretically, As long as dark wizard has mastered the method of making horcruxes, he can make many horcruxes like Voldemort. But Dumbledore said that except Voldemort, no wizard can split his own body into more than two parts and create more than one horcrux.

So it's not just murder. It depends on whether the way of murder is evil or cruel, and whether dark wizard's soul is evil or not. It can be seen that it is not just a simple murder, but the conditions are very harsh. Perhaps only Voldemort can make more than one horcrux.