Can I have two Apple IDs enabling two regions with a common Bank Details?

I personally, as well as other upper-level users with whom I am personally acquainted, have called Apple Support and directly asked if the payment method for a new Apple ID in a specific country must be a payment method from that country, and every time the Apple agent has verified that to be the case. The payment method must be from that country and the billing address for the payment method must be for that country.

My personal experience, as a bi-national with two Apple IDs, is that when I set up my Apple ID for each country, the payment method had to be one specifically from the country the Apple ID was for.

Mikera, to me this experience is what I share with users who ask the question that you've asked. For me that personal experience goes well beyond the realm of being Apple Support Communities folklore that some users who assert their superiority over the rest of us here might like to imply.

What was stated in an earlier post about a same country payment requirement is common lore on the forum but nowhere does Apple say that your payment method must come from the same country. I have read many versions of their documents and they very carefully avoid making what would be a very simple and clear statement to that effect. In fact what they say is, "For international credit and check cards, you might be asked to authenticate your payment method before it can be used.” You may wish to refer to: Payment methods that you can use with your Apple ID - Apple Support to see what Apple actually says (even their change country support article refers you to that).

It may be they impose a same-country requirement by some indirect requirement such as a billing address that meets the format for addresses in the country to which the statement is being set. We don't know how their system works.

Another take on this is practicality of using two IDs. To keep things simple, you can only have one ID on a mobile device at any one time. You would have to switch between IDs which would be a management headache, particularly if you subscribe to any Apple services such as iCloud+ or Apple Music. You may also encounter wait periods between being able to use those services. In the long run you may find it easier to simply own two mobile devices, each with its own ID.

You can have more than one Apple ID.

You usually have to have a payment method for your Apple ID. That payment method must be one approved for the country in which the Apple ID is domiciled. For example, a credit card must be issued to you by a bank in the country for which you've set up the Apple ID and have a verifiable billing address in that country.

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But from a practical standpoint there’s a high likelihood that the credit card issued in say London can’t be added to an Apple Wallet associated with a South African Apple ID and/or the iPhone physically in SA. OP would probably want to get a SA bank credit card to add to his SA phone, Apple ID etc.

But switching accounts between countries would be a pain. Carrying two iPhones would be a pain. While more expensive, it’s certainly more convenient to have one separate phone for each local. Each with their own Apple ID, payment methods, etc.