This heavily depends on if Sayaka, or anyone else that got into contact with Ashy, still counts as themself or as part of Ashy.
It has been heavily, consistently, repeatedly, and, again,
heavily implied that what Ashy subsumes is now also Ashy(from Ashtaroth's perspective, but Ashtaroth is kind of a very slightly omnipotent god, so what she believes...). (Which means that removing Sayaka is less a matter of reversing the process or excising a foreign object, but rather one of amputation. Sadly the "rip out her page" didn't work... maybe if she were actually inside of her page at the time? They could try getting a magical girl to rip out the page in much the same way that they would rip open a labyrinth...) This doesn't necessarily exclude them still being themselves though, unless there is some database-equivalent that I am not aware of that effectively indexes people's identities with only one entry(but alternative versions of individual people does seem to be a thing, so... the index theory does check out). There could still be only one Sayaka, with that Sayaka also being Ashtaroth. I feel as though the real questions are 1: Did Sayaka ever stop being Sayaka? Which I don't see anyone in-story opposing; and 2: Is there any Sayaka to oppose the existence of a Sayaka? Which... well there are (to my mind) hints that Ashtaroth's labyrinth is supposed to be significantly more distinct from the wider world than most labyrinth's are. A world unto itself, so to speak, when speaking thematically.
This is all massively complicated by the issue of Charlotte and Candeloro, who both likely don't exist under those identities at this time, and both had their barriers subsumed(?) into Ashtaroth's barrier, but neither of whom had their wills(?) and self-images(?) subsumed into Ashtaroth's own as Saar did, so are technically still largely free agents, and might even be able to leave the conjoined barrier based upon the example set by a certain planetoid who left upon a quest to pick up teenaged girls. It would be very interesting if Charlotte vanished, as it seems to be very likely that she was an explicit assassination effort by Kyube against Mami(it is like the critter has some personal vendetta against sustainable harvesting) and so the absence would be noticed, while conversely, Mami meeting her own witch would, well, result in a lot of confident denial, but might still involve fireworks, especially of Candeloro recognised her, or just realised that Mami had all of Candeloro's prized possessions...
It really is a messy issue, and ultimately comes down to Authorial fiat regardless of the reasoning, as basically all fiction is basically always authorial fiat...
