During this year's Google I/O event, the company did make a number of high-profile announcements and one of those which gained considerable attention was the upcoming launch of not one new app, but two. The new apps are Allo and Duo and while being different apps, they are sort of related. As well as being unveiled together, they both place an emphasis on communicating with other people. Allo does this by adopting a messenger-style functionality, albeit one which is vastly more feature-rich than the likes of Hangouts. While Duo places its focus on communicating with others via video.
While the apps have yet to arrive as available apps, they have since become available to pre-order. Of course, you cannot actually pre-order them, but you can pre-register to ensure you are one of the first to know when they become available. Now, in spite of the apps yet to become available, it seems as though they have gone through a fairly major cosmetic change.
It is currently unclear when the changes happened, but the icons for both apps in the Google Play Store have now changed. That said, they have not changed much, with the main difference being changes to the colors of the icons. Allo has gone from a white background to a blue one and its lettering has changed from Red to white. While Duo has gone from a blue background to a white one, with its lettering changing from white to blue. In short, Allo now seems to be adopting the coloring of the older Duo icon, presumably why both ended up being changed. As far as it can be seen, the Allo app changed yesterday, although it is unclear when exactly the Duo logo icon changed. As a result, it does seem quite likely that Duo's change occurred in the last 24 hours or so. Either way, the image above shows the older icons on top and the newer icons below. With at least one color change already being noted, there is no telling whether this will be the final design when the apps do launch. Google could simply be testing various designs and looks to see which works best for them. Although, as of right now, these are the current Allo and Duo icons.