Possibly, the correct interpretation is that AC didn't make the change - that the text of Liber L. dictated the change. But that's not the full picture, since we find a discussion by him in "An Essay Upon Number," which we wrote in August 1901. It's the essay in Equinox No. 5 where he was trying to analyze his way to the perfect number to express the Great Work.
In Part I, "The Universe As It Is," he summarized 11 as, "The Hendecad, the accursed shells, that only exist without the divine Tree. 1+1=2, in its evil sense of not being 1."
So, as you can see, he started with the G.D. perspective he had learned. (He was a relatively new G.D. 5=6 at the time, just to put this in perspective.)
We then go on to Part II, "The Universe As We Seek to Make It."
Here, we immediately find a very different perspective because, by the third paragraph, he's discussing ABRAHADABRA and so many of its characteristics. It's not clear how much of this was in the original, and how much was in the editing for publication in Eqx 5 a decade later (at least some parenthetical notes are clearly from later editing), but we can find a summary of his Part II view of 11 a few pages in, when he starts summarizing "the numbers which seemed to me to bear upon the problem." Of 11, he wrote:
"The great magical number, as uniting the antitheses of 5 and 6 etc. AVD the magic force itself."
That's the evolution he had already worked his way through, and probably reflects his mental space on the matter two and a half years later when Liber Legis was dictated. It affirmed some of his thoughts on number and blew some others (including some of the basic premises with which he began the 1901 inquiry) out of the water.
Love is the law, love under will.
Yours in L.V.X.,
Jim Eshelmanwww.jeshelman.com"Success is thy proof: argue not; convert not; talk not overmuch!" - CCXX 3:42