"What happened to your clone? How did she betray you and become the Witch Goddess Two Lips?"
Eren asked after pondering for a bit.
The natal clone was still the goddess' clone. As such, she should have been able to dictate her actions to a large extent.
Even if she allowed her some free will out of her own volition, she couldn't possibly allow the clone to betray the main body without a significant reason.
Eren's pseudo-avatars had "suicide bomb" mechanisms installed in them for this very reason.
One part of the reason was so that he could protect his identity in case of extreme situations, like what happened to one of his clones when he encountered Nira Nightshade.
The other part of the reason was so that the pseudo-avatars wouldn't betray him no matter how much freedom Eren offered to them.