Martin, this is a nice description of a well-known behaviour. It does not happen with each spawning that the eggs are being transferred to another place, but it is not a rare event. And sometimes they are transferred a second time and – perhaps – a third. Sometimes even larvae are transferred in this manner. This tranfer often happens in tanks with more than one cave, or with many leaves that are cave-like. Mostly, in the small breeding-tanks of experienced breeders only one cave is offered and readily accepted. If there is no alternative, then there is no choice for the pair and the male. And they don’t seem to feel uneasy.
Some species are more used to this transferring of the eggs than others; we have often observed it with parvulus and ornaticauda, but less often with others.
Your pictures give us nice insights into the breeding behaviour. And then it is not of great importance if they are not of the best quality. But perhaps you could post such a “bad” photo smaller than usual; that would be sufficient to identify the important detail that you want to show us.