After trial of several times, i figured it out that it was Possible to do stuff above.
I think this problem should be closed.
EDIT:
As mentioned in the comment that i should post the answer, so just modify the answer:
Yes it is Possible to register two webView to one obj, you just do what you do when you have only one webView, I did it wrong somewhere in the first place and worked it out later.
(Post it in case someone else encounter the same situation)