Perhaps it is, if only in the same sense that the Jesus of the apocryphal gospels is meant to be understood as the same person as Our Lord. It may be useful to think of the Koran as simply the last and strangest of the apocrypha.
If He is the same, why does He tell us that Christ is the only way to salvation in one book, and then invent an entirely different religion in another?
Why does one book consider Isaac to be the son of promise, while the other credits Ishmael. That doesn't match. If the two books are authored by the same "god", then he is a liar.
The Bible leaves no room to accept the Koran. The Koran does not teach that Christ is the only way to God. That means tha the Koran is a lie.
That's not too difficult for me to understand, and I'm not a rocket scientist.