Tried several times with several captchas. This is the data explorer page I tried to access.
with space between :
To the non-believers :) :
System produced on:
Chrome Version 33.0.1750.146
Reproed here as well
Note before typing in the correct numbers as above I deliberately typed in wrong ones and submitted. I expected the Captcha to change after the failure and present a new challenge but it didn't.
Maybe the server side expects a new challenge but this isn't refreshed client side?
Clicking the refresh button and trying again with the new challenge it succeeded.