There are numerous larger copies of this tiny work. Two that I reject are Ertz 1979 #s 284 and 285. Another version, not bad (better than 284!) but not genuine, sold Brussels, Palais des Beaux-Arts, 28.x.58 #451 (panel, 40 x 60); good photo of that at RKD. It was expertised by Friedländer in 1958 as Jan the Elder. A poor copy in Bowes Museum, Barnard Castle, 17 x 28.5 in.
In the present work, a lot of figures are heavily drawn but not very filled in, and the brushwork is not lively. However, in very small works like this it's hard to judge.