On the iPad. I'm filling out a form and it automatically puts any info I
type in one field into a similar field on the page.
It's pretty frustrating. If I then change the duplicated text it has
inserted, it changes it throughout the whole page.
It sounds like this was a poorly created form, not an issue with auto-fill. (I don't believe Reader for iOS supports that feature).
Basically what is happening is the PDF has form fields, and these form fields have hidden names. If one form field has a name identical to another, and a user inputs data into one, the other field will become populated with that data. It can be a useful feature when used correctly, but sometimes form creators accidentally name fields the same, and create this error.
I would contact the creator of the PDF and let them know that they need to fix their form.
Europe, Middle East and Africa