I've goofed.

I'll blame Alice.
I don't think it was her idea, but I'm sure she'd have nudged me.  I tend to Blip new plants; for a diversity of reasons.
1st of which is … However good Alice's memory was I doubt she'd have remembered date, let alone month an item came into the fold. Some time ago an online friend was bemoaning an inability to find any Sansevierias locally; almost immediately I found 2-3 pots of them, and bought one.
It consisted of three close-packed plants. I suppose I ought to have "bagged" one and left two together; having never seen one alone in a pot. Still, when repotting, the temptation's there and I succumbed.

I have now trawled back into October '18 and found no trace of this version; though quite a few of different dwarf varieties.
At time of repotting I noticed a wee pup, yet to break surface, beside one of them. It's taken till now to come through.
IF my trawl does find reference I'll likely come back and let me know.