which sentence is right?

Neither really make sense, unless the second "do" really is slang for engaging in sexual intercourse or slang for attacking.

Neither is correct because you can't "do" a noun; you can only "do" verbs.

EDIT: Ninja'd

Lol... I'm first who chose "yourself"... Think I'm not enough good in English

As pointed out, both are incorrect as they rely on slang - Slang might work sometimes, but it'll always cause issue with some specific sentences (such as this one). Your best option if you absolutely must use "do" as a slang in the second part of the sentence, is to eliminate the "do" in the first part.

For example; "If you carry out [action], I will do you."

Also, in any case "yourself" is incorrect - "Yourself" is reserved for situations where a second person won't get involved "you did it yourself", "you can do it yourself" as far as I know. I'm no English expert, I'm just going by what I know.

The death sentence.

Personally I have no problem with the slang. Going off what you've said, the first one makes more sense because 'yourself' should only be used in this context if they are also the one about to follow through with the action.
e.g. If you do, you will do yourself.

It is 'them' + their 'self'. The 'self' is used to differentiate 'them' as a pronoun in place of a proper noun vs. 'them' as a pronoun describing them as a noun. Similarly:
e.g. If you do, I will do myself.

Putting aside the, uh, logistics of achieving this, the structure is the same. You only need to use the 'self' if there is another pronoun referring to the same person in the same clause. I think. I hope that makes sense...

Neither is right. They are both left (justified).

Regardless of the meaning of the word "do" or any missing words, one of them can never be correct. "I" can never act on "yourself". Only you can act on yourself and I can act on myself. So that one is wrong. Whether the other one is right depends on what you failed so hard to censor.

So when's the baby coming?

"If you do, I will do to your personage." is the closest to the original sentence that can make a proper sentence I can think of. This retains any sexual connotation you may be intending to imply.

I think instead of "do", you should probably just use "bang".

Then "I will bang you" is correct

Sounds like you ripped that straight from some cheap bootleg subtitles ;D.

Definitely not the one with "I" and "yourself" in the same phrase. But neither works because you can't use "do" twice if it doesn't mean the same thing. One of them has to be something else, because from the very little context given it's clearly not the same thing.

"If you pay me, I will do you."
"If you do, I will leave."
"If you put that on, I will do you."
"If you do, I will **** you."

Obviously "do" just represents something more concrete. So you can't use "do" twice unless it means the same thing.

"Don't drink that water. If you do, I will do as well!"

I guess you meant
"If you do me, I will do you"
Although one runs the risk of engaging in a 68'er
What's a 68'er?
It's a 69'er where you do me and I owe you one ...