The only official teaching on such a thing is the Catholic Canon of Scripture itself.
The fact that there are many varying manuscripts is just an archaeological reality. Moreover, it's self-evident because various translations omit different phrases or verses or the same verses might contain slightly different language.
Case in point:
Matthew 6:27: Some translations reads:
The New King James reads:
27 Which of you by worrying can add one cubit to his stature?
Whereas the New International Version reads:
27 Can any one of you by worrying add a single hour to your life?
Now the first part of the verse is clearly just a different translation of the same Greek words to English but the last part of the verse indicates a different original Greek text. The underlying meaning is the same but the examples of what you can't do, by worrying, are different.
We aren't sure but when we dig further and look at the parallel text in Luke 12:25 we see the same exact phenomena.
The King James 2000 again uses cubit and the New International Version uses single hour.
So this seems to indicate that whoever copied these ancient manuscripts were consistent but, bear in mind,
contemporary translators don't always rely on only one manuscript so it could be the choice of the translators.
There are all kinds of variables but the underlying point remains the same: There are obvious differences between
the various ancient manuscripts . . . none of which amount any doctrinal differences, as we don't base doctrines on single Scripture verses.