They are just the synonym.
- Sakkāya is an object of anu-diṭṭhi. So, sakkāyadiṭṭhisutta and
attānudiṭṭhisutta have the same content. This is the english translated version of those suttas,
attānudiṭṭhisutta is next of sakkāyadiṭṭhisutta.
Your 3 suttas, which near by each other, describing each other like this:
Diṭṭhi means misunderstanding of causes and effects, clinging-aggregates which is anattā as attā.
Anu is prefix which means often.
Micchā is prefix which means mistake.
Sakkāya is a name of clinging-aggregates follow to many sutta, such as Sutta. Ma. Mū. Cūḷavedallasuttaṃ.
These clinging-aggregates are the Sakkāya described by the Blessed One.
So, sakkāya-micchā-anu-diṭṭhi means often mis-understanding, micchā-anu-diṭṭhi (verb act as noun), of sakkāya (object), causes and effects, clinging-aggregates, which is anattā, as attā. See note0 below for more information.
Note0: (I have to use image, because I can not make underline in stackexchange. The same format are relating to the same format.
Above pāli appear in these suttas:
Sutta. Saṃ. Saḷa. Isidattasutta:
For "dvāsaṭṭhidiṭṭhigatāni brahmajāle" above refer to micchā-diṭṭhi in Aṅ. (2): catukkanipāto saṅghabhedakasutta:
So, what I said:
It is completely from pāli.
Note1: Sakkāya is not only internal, because there are internal clinging-aggregates, internal sakkāya, and external clinging-aggregates, external sakkāya, which are contemplating by the practitioner in Cūlavedallasutta and Sutta. Ma. Mū. Sacca-pabba of Satipaṭṭhānasuttaṃ (<< this link is a good translation of this sutta).
they meditate by observing an aspect of the principle inside and outside.
The inside and outside aspect of the principle in this term is sakkāya (clinging aggregates), sakkāyasamudayo, sakkāyanirodho, and sakkāyanirodhagāminīpaṭipadā.
Note2: Santo kāyo sakkāyo. Kāya, clinging-aggregates, is sacca, santa, vijjānana, the reality, truth, possible to arise in causes and effects cycle. So, buddha said sakkāya is sacca and clinging-aggregates in Sutta. Saṃ. Kha. Sakkāyasutta[trans].
"Sakko kāyo sakkāyo" and "para kāyo sakkāyo" is allowed in Ma. Mū. Sacca-pabba of Satipaṭṭhānasuttaṃ as an internal anupassī, but it is not the primary meaning when compare to Sutta. Saṃ. Kha. Sakkāyasutta[trans], which sakkāya meaning is defined by buddha directly. And "para kāyo sakkāyo" never found in any where else except in Satipaṭṭhānasuttaṃ.
So, if you use "sakko kāyo sakkāyo" in Sakkāyasutta, Sakkāyasutta, which has only sakko, will conflict with Sacca-pabba of Satipaṭṭhānasuttaṃ, which has both sakko and paro.
But by the "Santo kāyo sakkāyo", there is no conflict like that between the co-context sutta, such as micchādiṭṭhisutta, sakkāyadiṭṭhisutta, and attānudiṭṭhisutta, which using the same context and near by each other. Also, there is no conflict between those sutta and the faraway suttas such as Sutta. Saṃ. Kha. Sakkāyasutta, Sutta. Ma. Mū. Sacca-pabba of Satipaṭṭhānasuttaṃ, and Sutta. Ma. Mū. Cūḷavedallasuttaṃ.
Note3: Your 3 suttas, which near by each other, describing each other. Mostly words of them can use in the other sutta, such as anicca, dukkha, anatta, of these 3 sutta contexts all refering to saṅkhata (clinging-aggregates), which means arisen by causes. So, it can use to explain each other like appeared in Vinaya. Mahā (1) Anattalakkhaṇasutta:
- ‘Now what do you think, O bhikkhus, is the body permanent or perishable?’
‘It is perishable (anicca), Lord.’
‘And that which is perishable, does that cause pain or joy?’
‘It causes pain (dukkha), Lord.’
‘And that which is perishable, painful, subject to change, is it
possible to regard that in this way. ‘This is mine, this am I, this is
my self (atta)?’ ‘That is impossible, Lord.’
So, those 3 suttas is synonym of each other. For the example:
You never have to see "I often(1) mis(2)-understand(3) of you-ahaṃ tuvaṃ micchā(2) anu(1)-passāmi(3)" sentence. But is it the right, if I tell you A, B, and C have the same meaning?:
A: I often understand of you as permanent person.
B: I misunderstand of you as permanent person.
C: I understand of you as my dear forever (misunderstanding sakkāya as attā).
In this case the buddha can predict, because buddha maybe his teacher, the listening-bhikkhu will enlighten by animitta-vimokkha, so the buddha taught impermanence to him. And this bhikku maybe memorized micchādiṭṭhi from buddha before, so the buddha taught micchādiṭṭhi in this sutta. If the buddha teach the other words, they cannot enlighten, because the listening maybe never memorized before.
It looks like when I said หนึ่งคูณสองเท่ากับสอง, you cannot enlighten what I said. But if I said "1x2=2", you can get it.
This is the same way which atthakathā described SN Salāyatanavagga aniccatādisutta:
Iti idaṃ suttaṃ chasu ajjhattikāyatanesu tīṇi lakkhaṇāni dassetvā
kathite bujjhanakānaṃ ajjhāsayena vuttaṃ.
For these 3 sutta, buddha taught 3 characterizes of 6 inner-āyatana
depend on the enlightening-possibility of each listening-bhikkhu.
For more information, you can see naya in netti.
Note5: Sakkāya is not similar to sakkāya-diṭṭhi in mostly suttas such as sakkāyasutta.
Sakkāya is 5 aggregates, which is engaging by diṭṭhi-clinging (diṭṭhi-upādāna).
But sakkāya-diṭṭhi is diṭṭhi-clinging, which engaging 5 aggregates.
So, mostly english version, which I random checked, translated wrong as "self view (sakkāya-diṭṭhi)", but it should be just "sakkāya".