Can the original ECU be replaced with other ECU codes on the same vehicle?

No. If you can't get the exact number ECU, send yours in to be rebuilt. Do not use a different part #

Many ecu's will have the same hardware number and just different software. Some part numbers are even just different calibrations for the same system. I do not know the ecu in question here to answer the questions fully but it is common to use different part numbers when replacing the ecu. Some cases its easy to downgrade or change software and can be done with the manufactures flashing software and sometimes its not as easy but doable with the right tools. As long as the hardware is the same then it can work. However if your not sure of what your doing or the skill of your mechanic doing it, it is probably best to match all the numbers for simplicity.

Generally in ECU if hardware version is match then you can download any compatible software to that hardware and it works without any issue.

You must be sure about hardware version because in many ECU hardware version is not clearly mention, In that case you can open the ECU and see PCB version and components.

Please note that when you clone software from one ECU to other then also copy EEPROM other wise it will give some error or it may not work.

Especially Kia ECUs cannot be reused as once the VIN is written to them, you cannot unwrite them.

In the least you would need a reprogram once swapping, as your local Professional Automotive Repair facility about this repair and if they have a machine that can rewrite VINs into ECUs like we do at mine.