How many kinds did Noah bring into the ark,
two or seven?
Genesis 7:2-3 and Genesis 6:19-20
Genesis 6:19-20 simply instructs Noah to preserve two of every kind. Genesis 7:2-3 is additional information where seven of the clean animals were to be taken and two of every other kind. The reason for this is that the extra animals were for sacrifice. "Then Noah built an altar to the LORD, and took of every clean animal and of every clean bird and offered burnt offerings on the altar," (Gen. 8:20).
Logically, to have seven pairs also means that there are two pairs, since the two are included in the seven. If one verse said take only one pair and another verse said seven pairs, that would be a contradiction.