Tleilax Master B wrote:"No Face Dancer," Edric said. "A Face Dancer risks exposure under prolonged surveillance. No; let us assume that our wise Sardaukar commander had Idaho's corpse preserved for the axolotl tanks. Why not? This corpse held the flesh and nerves of one of the finest swordsmen in history, an adviser to the Atreides, a military genius. What a waste to lose all that training and ability when it might be revived as an instructor for the Sardaukar."
Edric rolled in the tank, bringing his attention to bear on the ghola. "This is a man called Hayt," he said, spelling the name. "According to our investigators, he has a most curious history. He was killed here on Arrakis . . . a grievous head-wound which required many months of regrowth. The body was sold to the Bene Tleilax as that of a master swordsman, an adept of the Ginaz School. It came to our attention that this must be Duncan Idaho, the trusted retainer of your household. We bought him as a gift befitting an Emperor."
I am a ghola, he told himself.
That had been a shock, but he had to believe it. To find himself living when he knew he had died, that was proof enough. The Tleilaxu had taken cells from his dead flesh and they had grown a bud in one of their axlotl tanks. That bud had become this body in a process which had made him feel at first an alien in his own flesh.
I think there may be confusion in previous posts about the perceived differences between making a ghola in the time of DM and in the time of HoD. I think all instances of creating a ghola across all the books are exactly as OP quoted, in the way described in DM. Parts of the original body of a person are taken shortly after death by the BT, and are regrown and revitalized into a living state. There is no copying or 'reproducing from scratch' the genetic equivalent of an individual - it's actually that same individual, brought back.
Think quickly about the quote above involving the regrowth after Duncan's head wound. The next question is - how much more of him could be missing and still allow regrowth to be complete? It is certainly likely the BT improved their techniques over time to be able to regrow a person from less and less remaining material. If we follow this thought through we arrive at the conclusion that they'd eventually be able to regrow a body that was reduced even to one cell in size. This definitely would allow them to regrow several incarnations of the same person - each one being that same original person brought back to full health. But this isn't cloning!
Cloning of organisms, as we know it (far be it for me to suggest there will never be another kind), involves implanting an emptied egg with genetic material and then placing that egg in a female as it replicates. While I'm certain the people in the Duniverse can easily accomplish this (although I suspect it is universally banned) it is a completely different procedure than what I think it is the BT do. The BT grow back an individual "Wolverine-style", reconstituting the body fully from some amount of remnant material; think of it like regeneration. I also think they probably developed this technique precisely because cloning was banned, while 'healing damaged persons' was obviously allowed. Using bodily regeneration as the equivalent of necromancy would have been repugnant to many, but hard to legally classify as much different from healing.
The thing they obviously learned is the similarity between cellular regeneration and between mitosis, and found that a uterus could be used for either purpose. They probably also learned how to adjust the uterus to influence the regeneration process, so that the regenerated body had properties the original didn't.
While I do think the idea is cool that the original Axlotl tanks were mechanical tanks and that the BT only later learned how to use their females, I find this explanation unnecessary since I don't think the ghola process ever changed appreciably. I also somehow doubt the BT ability to develop this strange technology at that time when it was Ix and Richese that specialized in machines. I also think that the omission of the mention of BT females until the later books was quite intentional right from DM, indicating that the females were always the 'tanks'.