Possible omission

Question

The sentence is taken from the Manga Death Note:

(I put spaces where the sentence parts are separated within the speech bubble...)

「ワタリには　自分の身にもしもの事があった場合　自分でできれば自分でできなければ　一定時間ワタリが携わらない事で自動的に　全データを消すように言ってあります...」

There is a small space between the 「自分でできれば自分で」and the 「できなければ」. While I get what the sentence means I was wondering where the second 「自分」 belongs to. From my interpretation the 「自分でできれば自分で」 is one constituent and in 「できなければ」an additional 「自分」is simply omitted because we do not need it to understand the sentence, isn't it?

In other terms: Could the part be replaced by: 「...自分でできれば自分で 自分できなければ...」? I fully understand that this sound rather clumsy, but it is not grammatically incorrect or is it?

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Edit:

Adressing the answer already given:

I did not want to say that in 「自分でできれば自分で」 the second 「自分」is modified by 「自分でできれば」I thought that it is more or less an abbreviated form of 「自分でできれば自分で全データを消すように言ってあります」. I am not sure whether that is grammatically possible; however, I assumed that one could use that to put a certain stress on the phrase. I guess you could translate it as: If he can do it himself, he will delete all data by himself. So, my general idea was that 「自分でできれば自分で」can put a certain stress on who does the action.

Addressing the second part of the answer:

I think I was not clear enough in the original question, but I did not intend to say that 「自分で自分できなければ」is correct. I fully understand why that is ungrammatical, but I did not consider these to form a constituent in the first place; what I meant was that 「自分でできれば自分で」form a constituent; The second 「自分」would be part of 「自分でできれば自分で」not of 「自分で自分できなければ」.

Answer 1

I'm sure that almost all the Japanese interpret this as below although it has very complicated grammer as you suffer from building up. (Perhaps we may needed more story context for interpretting this sentence. I know the story of "Death Note" by the way.)

Actually the below translation is correct in this case.

「自分でできれば自分で　できなければ　一定時間ワタリが携わらない事で自動的に　全データを消すように言ってあります...」

If he can do it by himself, (he will remove all the data by himself), but if he cannot, all the data will be removed automatically after a while without doing anything. I told him to do so.

So

I thought that it is more or less an abbreviated form of 「自分でできれば自分で全データを消すように言ってあります」.

This is grammatically CORRECT as long as "自分でできれば" modifies "データを消す" not "言う. And it means 'If he can do it by himself, he will remove all the data by himself. I told him to do so.' It is reasonable and correct interpretation.

「自分でできれば自分で(...)、できなければ...」

This is common pattern like 「自分でできれば自分で、できなければ私に聞いて。」 meaning 'Please do it by yourself if you can. Otherwise ask me.'

「自分でできれば、自分でできなければ...」

On the other hand I've hardly heard this pattern. I think we generally don't connect 'できれば' and 'できなければ' directly without target of 'できれば' condition.

We use '自分でできても、自分でできなくても...' instead, meaning that 'No matter whether you can do it by yourself or not.'

Answer 2

There's no omission.

There is a small space between the 「自分でできれば自分で」and the 「できなければ」. While I get what the sentence means I was wondering where the second 「自分」 belongs to.

This is simply saying, "if [I] can do it by [my]self, [or] if [I] can't do it by [my]self". (Bits in square brackets are not explicitly stated.) I'd interpret the small space between the second 自分で and the できなければ as indicative of a slight pause by the speaker, as if they're unsure of themselves or worried about what it might mean if they can't.

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From my interpretation the 「自分でできれば自分で」 is one constituent and in 「できなければ」an additional 「自分」is simply omitted because we do not need it to understand the sentence, isn't it?

That interpretation doesn't work. The first part ends at できれば. This is the verb できる ("to be able to do something", sometimes also "to come into being, to become apparent"), in the conditional or hypothetical conjugation ending in ば. This cannot modify a noun, so we know that this initial 自分でできれば is not modifying the following 自分で. From the grammar of how できる is used, we also know that the 自分で (or really, [PERSON]で) is a common construction for this verb, meaning "able to be done by [PERSON]".

From this, we can tell that the second 自分で must be the actor of the final できなければ. This complete phrase is simply the speaker laying out two contrasting possibilities. As English, this might be translated as something like:

If I can do it myself, if I <pause> can't do it myself...

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In other terms: Could the part be replaced by: 「...自分でできれば自分で 自分できなければ...」? I fully understand that this sound rather clumsy, but it is not grammatically incorrect or is it?

This is not grammatical. As noted above, ～で + できる is a common construction pattern, so 自分[で]{●}でき[る｜なければ｜etc.] would be the expected pattern.

Also, you wound up with 自分で 自分できなければ. Let's analyze this:

• 自分で 自分できなければ
  [自分]{oneself}[で]{by}   [自分]{oneself}[で]{by}   [き]{wear (STEM)}   [なければ]{not (HYPO)}

The meaning is different, with the speaker stuttering about "by myself" and then using a very different verb -- きなければ must be 着なければ, based on the verb 着る ("to wear something [on the upper body]"). But that's nowhere in the original text.

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Please comment if the above does not address your questions.