Who told you the deuteros don’t belong in the canon? How did God reveal this to you?
quod.lib.umich.edu/k/kjv/browse.html
There is a KJV online (see link above) that contains the deuteros. They are placed at the end in a separate section called “Apocrypha,” a word that means “hidden” and is generally used to mean “noncanonical” when referring to the Scriptures.
molcat1.bl.uk/treasures/gutenberg/search.asp
When I look at the Gutenberg Bible (see link above), I see that the deuteros are included with the other OT books. The reason why they are included with the other books is because they are considered part of the the OT canon–they are canonical books.
On the other hand, when I look at the online KJV that has the deuteros separated out and labeled as “apocrypha,” it is clear to me those who assembled and published the KJV did not consider these books canonical.
So, looking at the two different versions of the Bible, it’s clear the Gutenberg includes the deuteros as part of the OT canon while the KJV includes the deuteros as apocrypha. It should be obvious to anyone who looks at them.
As to your question of why those who published the early KJV included the deuteros in their Bible? They probably felt uneasy removing the deuteros entirely from their Bible since every Bible printed or copied before the Reformation included these books. Apparently, as time went by, the uneasiness subsided since now hardly any Protestant Bibles contain these books.
(Here’s an aside about the KJV and the apocrypha–I read that in England, if you take an oath on the Bible, it must contain all the books of the Bible–including the 7 deuteros Protestants now reject.)