So I separated my two keikis, affectionately known as the Twins, a while back and I just noticed this little growth on one of them. For whatever reason, I generally kill Phalenopsis so I haven't seen this before. Are they making another keiki?
Is it usual for them to create another so quickly? I have them in bark with a significant quantity of PrimeAgra on the bottom for drainage. They seem to be doing well (no obvious signs of distress or rot). I thought they generally only keiki when they are are under distress?
There are several species which willingly multiply by growing basal keikis. Obviously you have some of those in the background because the large plants look very healthy.
I have seen it described as Siamese twins. You might be able to separate once they both seem to have roots, but it might cost you the life of whomever is weaker or kill them both and in that case it's much better to keep them together and maybe they'll flower at the same time.