After moving to a new server we had some serious issues with server side caching of ota updates. What happened was that, instead of "calculating" the response for every single ota request, it would hold a 5 sec cache.
In practise this meant that if 2 devices called home for an ota update within the same 5 sec time frame. The second device could receive the update generated for the first device.
This is a serious error which should not have happened. But as it did, we believe being open and transparent about it is the only way forward.