Can i get all my imessages on both iphone and ipad?

Yes, update to IOS 6.

The Apple Support Communities are an international user to user technical support forum. As a man from Mexico, Spanish is my native tongue. I do not speak English very well, however, I do write in English with the aid of the Mac OS X spelling and grammar checks. I also live in a culture perhaps very very different from your own. When offering advice in the ASC, my comments are not meant to be anything more than helpful and certainly not to be taken as insults.

http://osxdaily.com/2011/10/19/sync-imessage-across-all-ios-devices-iphone-ipad- ipod-touch/