I was upgrading a front wing, but probably double clicked on upgrade.
This resulted in just1 iteration being developed, while it did cost me double the development points.
The production was correct, in producing 4 parts, where 4 parts were paid.
I had expected either an error, or a 4th iteration to be developed (still based on iteration 2).
As you can see in the image, the front wing development only shows up once in the news, and in the development tab, whilst I did pay twice for it, as can be seen in the modifiers.