Update list.php

hmmm. yes your question is correct. why i added disabled and readonly both?!!
I think i do not added both of them to my component's form's xml. in my component i needed to disable or readonly some forms fields based on some fields values in load form function. then some fields may have both of readonly and disabled values together.
now when user save form, in save function i run some function based on fields that user submitted.
i can do very things to fix that input do not have both attributes. but this is more simple.

now your solution is better. i search web and understood that disabled attribute will not work with hidden inputs. (http://www.w3schools.com/tags/att_input_disabled.asp)
sorry for my mistake about this.

now i fix my pr.