Why does Play Store update twice in a row the same app to the same version? Why does Play Store (formerly Android Market) mark for update twice in a row the same app to the same version?

Here is a typical example of what happens. Yesterday I checked the My Apps section from Play Store, saw that version 3.5.1.1 of the Kindle app was available for update, and updated it. Today I checked the My Apps section again. Play Store showed as available for update the same 3.5.1.1 version of Kindle with the same release notes. I updated the app again.

The same often happens with other apps, both on Android Market in the past and Play Store now. The second update is available the day after the first (I check daily for updates). In all cases the apps are correctly donwloaded and updated, and run fine. All my apps are set to manual update.

I have an unrooted Nexus S running Android 2.3.6 and my phone carrier is Vodafone Italy. I have Play Store 3.4.7. The issue happens with both 3G and Wi-Fi.
Update: It is probably a "hot fix" of application developers, which they've spotted few moments after the update release. As solution it is easier to release an immediate second update with the same version number (ver. numbering is solely on app developer). So it ends up twice (or even several times) after the first update. Also, IMHO, the same version number ensures that users, who did not updated with the first "buggy" wave, will receive the last "hot fixed" update of that number. This was confirmed in some case here.

Original post:

Maybe this issue is connected with multiple google accounts? It could be intersting to check next time this happens if both update proposals are for the same account.

Second thought: did the update go well in the first attempt?