The speed limit between BZA-VSKP is 110kmph only. There is no clearance for higher speeds on this route so far. The permanent way is also not yet upgraded for higher speeds.
LP's don't overspeed either, as since the advent of 3 phase locomotives, trains speeds are strictly monitored and LPs often receive harsh punishments for over-speeding. In all likelihood, it was just a GPS error on your speedometer app.
"Kharagpur - Waltair - Vijayawada falls under B class This class allows speeds up to 130km/h." - Small correction here. Class B routes...
more... are suitable for "upgrading" to be capable of 130kmph. These routes just have the necessary ground work already completed so that they can be upgraded for 130kmph. They are not fit for, nor do they support 130 kmph speeds.
You can see that there are many class A routes in IR, but only the Palwal-Mathura stretch is suitable for regular operations at 160kmph. This is because, class A means that the route can be 'upgraded' for 160kmph easily. It doesn't mean that the route is currently capable of 160kmph.