Balancing Payment plus 1st Payment on Account

Hi, this is my first tax return. I am having trouble understanding why the balancing payment (which is the same figure as tax due) has the 1st payment on account figure added to it. This is then what is due for 2023/24. Am I mis-reading?

Hi Helen Lynch,
If you file a tax return where the balancing payment owed is more than £1000, two Payments on Account (POAs) for the next tax year will then be scheduled.
These POAs total a prediction of what you will owe for this next tax year.
The first POA is due on the 31st of January (10 months into the tax year in which the amount is technically owed)
While the second is due 31st of July (4 months after the end of the tax year which the amount is owed for).
POAs ensure that the majority of the tax that you owe for a tax year will be paid before you file that year's tax return, while still allowing more time for that tax to be paid than PAYE taxpayers receive.
You can read more here:
Understand your Self Assessment tax bill
Thank you.