Just discovered a 'pair' of 2x8GB Vengeance LPX I bought on ebay are in fact different revisions. Not impressed.....
V4.24 is double rank
V5.30 is single rank
They also have different timings at certain clocks.
Even though their XMP 3000MHz timings are the same, I guess the chance of them actually working on a Ryzen motherboard at said speed is vanishingly small?