When you are logged in in fireplace and you install an *app*, it sends a request to the API to record that this app has been installed on your account. That same record is requested on startup by fireplace to show you apps that you have installed in the past but may be absent on your device (useful for people with multiple devices, but most importantly for paid apps you have paid but might have uninstalled) The code that records this in fireplace is in the user module, in update_install(). It stores an id. From what I can see looking at my logs when installing an addon, we also call this when installing addons, and we shouldn't, it would mark random apps as installed if the same id is used by an app and by an addon. For instance, if the app id 42 exists, and I install the addon id 42, then it would record that the app 42 is installed, (and it would appear in "my apps") which is wrong. We don't need that mechanism at all for addons, so we should not call it for addons.
I thought we were in the clear in terms of ID overlap (but my memory is admittedly fuzzy on this)?
It's a bug, but it's not very severe. How likely is it that someone is going to try to install an app and an add-on that both share the same ID? There are so few addons, the IDs are under the hundreds. The ID for apps are like in the tens of thousands no?