I really think this is a common Thai grammatical error. In the second half of the last paragraph, the sentence starting with "A copy of the health insurance policy......." should have the word "only" after the words "copy of". That's how I am reading it.
Just for info, this notice now appears on the website of the Thai Embassy in Canberra, Australia. For those with concerns it might also be worth checking websites from Embassies in other countries.
The first paragraph is what I have posted separately about.
On my four return trips to Bangkok I have always entered my Visa Number in this space and have never been pulled up. After what Geoff passed on, should this space be left blank, even though the heading is “Visa Number”?