Every time you sleep, you kill yourself, meaning the person you wake up is not you, but the person who has the same exact experience as yours. And the current YOU is nothing but a person who took place of the yesterday's YOU. Your self is shaped through your experiences, circumstances, difficulties, problems, bad moments, sad moments, angry moments, happy moments... literally everything you have ever gone through throughout your whole life.
Another interesting question would be, what if the current YOU and your childhood YOU meet, Who is the more complete YOU. One might say it's the current version of mine because I am more mature than young me, but are you really? Imagine your future self 40-50 years old coming and taking over your body and justifying it by saying that he is more 'mature' than you and it's essentially 'his body'. Will you agree? Will you let him take over your body and let him live your life? I don't think I would cause to me he is a different person, a stranger perhaps is a better word. Even though he is me. The future me might have been the same person as me at one point in time but now he is a different person.
Now to your question, technically he is not YOU, but he is a YOU from the future, thus a stranger. Not exactly a clone but a person who is just like YOU, might show the same habit as YOU and might even make the same decision as YOU. I am using might here because just the experience of you dying and waking to a different world will change YOU. And finally my answer to your question, according to my opinion is that he is a different person(not a clone but a different person) who thinks he is YOU. But then again by this logic, you are also a different person who thinks that he is YOU.
YOU or your sense of self is nothing but a consciousness that has surfaced after you have experienced whatever you have experienced in your life.
And it's 2 am, and I am really proud that I wrote such a wise-sounding answer, and feel like I have discovered something really great and now I am imagining myself winning the Nobel prize for this. I think I should just sleep/kill myself and let another person (who thinks he is me but actually, he is not) take over my body when I wake up the next day. good night you will never see me again and if you see me, it will not be me but a different person wearing a body that has housed thousands of ME. I only hope in my short life span of a day, I have brought a smile to your face. :)