I am getting a varying difference on occasions between my VP@ and BoM (Aust) manual gauge.
Last rainfall was 0.6 mm diff in 10 mm - VP2 high. Rain was steady for period with little or no wind … Gauges are approx 2 m apart and installed to spec
Does anyone else have a manual setup and getting a diff between the two …??
If I have learned one thing about comparing rain gauges from membership of this forum it is this: “that way madness lies.”
I am willing to bet that if you arranged seven, e.g., BoM gauges in a close-packed hexagon that the readings would differ. So what chance is there of VP2 and BoM gauges two metres apart agreeing? Are they at the same height, for instance?
0.6 mm difference in 10 mm is pretty close, IMHO 
And yes, I have used a CoCoRaHS-type manual gauge as a check and a backup for my wireless stations (admittedly not Davis) for some years now. It can be useful when the tipping bucket batteries are getting low.
I do realize that there are variations, but looking at my records I find some bigger ones that to me should not be of great magnitude.
For example, VP 2 32.6, BoM 29.6 = 3 mm / VP2 48.0 Bom 44.4 mm= 3.6mm, a 9.2% and 7.5% difference.
BoM Gauge is per spec and VP2 gauge is at recommended height.
I am aware of the variations that occur with storms and wind etc, but steady vertical rain should not give much of a variation.
As an ex-BoM observer & Tech officer, accuracy is critical, as these differences can add up to a significant annual variation.
I must admit that the rainfall section in WD gives me some concern with the reporting accuracy and number of ways it fails and varying methods of so-called corrections, as I have had considerable trouble trying to do so. That is why I keep manual readings.
I find it interesting your VP2 is reading higher than your manual gauge. Like @bitsostring, I compared a manual CoCoRaHS manual gauge to my VP2 tipping bucket for many years. Unless heavy rain occurred, they were typically within 0.01-0.03" of one another. Living in Florida at the time, heavy rain in thunderstorms resulted in an average 15% error, with the VP2 always recording less rain because the tipping bucket couldn’t keep up with the rain rate, which is a known issue for tipping bucket style gauges.
Not sure about that, statistically. . .or stochastically 
If your VP reads consistently high it might be worth checking the calibration? I seem to remember a figure of 544 ml per inch for the US version of the tipping buckets gauge, but I don’t know about the metric version.
EDIT: I checked a few posts over at wxforum.net and looks like the equivalent metric figure is 21.41 ml per mm (for a tipping-bucket gauge with funnel diameter 6.5" or 165.1 mm, area 214.1 cm²).
Also found this, from the boss of the main Davis distributor in UK.
Agree re rain problems in WD. I have a new one: since changing from OS WMR200 to Ecowitt GW1102, WD only puts rain into “Last 7 Day’s Rainfall” 24 hours late. . . Everything else rainwise seems OK.