Double check it against what information source? The malicious software has altered the one shown on both devices. They will of course match, but not with the one you're actually meant to be paying to.[0][1]

[0]: http://www.reddit.com/r/Bitcoin/comments/23sjle/chrome_exten....

[1]: http://www.reddit.com/r/Bitcoin/comments/1vrium/a_google_chr...