For the last couple of months I've been noticing a strange behaviour in the Android SDK Manager. The recently introduced Android SDK Build-Tools don't seem to get updated but instead are recognised as separate packages
The list keeps growing and it kind of disturbs me. Now whenever I see a new package I resort to just uninstalling the older version and installing the new one because I suspect there might be version conflicts if I have multiple instances of the same package installed
Oddly enough, this behaviour is shwon by every SDK Manager on my system (I have multiple ADT installations in use) and so I ask myself:
Might this be on purpose? If so: what's the reason behind it?
I would gladly accept that if it is so, but when I was searching for this issue on the interwebs all I can seem to find in screenshots is the expected behaviour: one package that gets replaced when it is updated (like the Android SDK Tools for example). I have so far not been able to find one single thread/blog/post where someone complains about this
The reason is simple
"What if someone requires to download the older version for compatibility purposes"
If the ADT overwrites the entry for every new revision or version to the software, user won't be able to download the earlier version because they are together grouped under "Tools" and not as separate versions as in "API SDK"
来源：https://stackoverflow.com/questions/19785584/multiple-instances-of-android-sdk-build-tools-bug-or-feature