It was a sharp student in the Bible study class who picked up on this one. "In the story of Noah and the ark, in one place God tells Noah to take a pair of each animal into the ark, in another place it says seven pairs of the clean' [kosher] animals. Later it says Noah took two of each animal into the ark. Now which is it one pair or seven?"
Here again we discover the authorship dilemma of the Torah (the first five books of our Old Testament). Tradition says these are the books of Moses; however, few scholars embrace Mosaic authorship today. Instead it is generally accepted that the Torah is a compilation of at least four different authors with editorial excerpts from yet another. In the account of Noah's ark we can easily identify two authors designated J and E.
The writings of these two authors are unique from each other in that they use different names for God. E uses the Hebrew name "Elohim," translated in the Torah as "God." J, however, uses a different name for God, "Yahweh," translated in the Torah as LORD. One clear way to divide the author's works is through realizing E never uses the word "Yahweh." For instance, there are two creation stories, Genesis 1.1 2.4a was written by E. However, Genesis 2.4b 23 was written by J, again the appellate for God being the giveaway. Notice, though, the two creation stories could each stand alone as a whole.
When we look to the passages of Noah's ark we see the distinction of two authors as well. There are lengthy passages where God (Elohim) is the name used, while there are other passages where LORD (Yahweh) is the name used. However, unlike the creation accounts which stand side-by-side, the stories of Noah and the ark have been compiled and intertwined. What becomes most interesting, though, is when we separate E from J and read the two stories both stories are essentially complete!
Let's compare the synopsis of the stories (space doesn't allow the two stories be printed in their entirety). E wrote the passages Genesis 6.9-22; 7.6-15; 8.1-17; 9.1-17. The story goes like this: Noah was righteous in his generation, but the earth was corrupt and filled with violence. God decides to destroy all living creatures, but tells Noah to build an ark. The contruction design is detailed and God tells Noah take one pair of each of the animals into the ark with him. Noah follows God's orders taking "Of clean animals, and of animals that are not clean, and of birds, and of everything that creeps on the ground, two and two, male and female, into the ark with Noah, as God commanded" (Genesis 7.8-9). Next, the exact date of the flood is given (second month, seventeenth day) and it rains for forty days and nights. One hundred and fifty days later the waters subsides and Noah discovers the land is dry enough to disembark. He does so, the animals are released and God makes a covenant with Noah (with the rainbow as a sign).
This story stands complete in itself even with the large sections of the J passage removed.
But J can stand alone as well. J wrote the passages Genesis 6.1-8; 7.1-5; 7.16-24; 8.18-22. It's story is like this: People on the earth become involved with the "sons of gods" and the Nephilim (giants/heroes) and God saw humanity becoming "great" as well as evil, so God decides to put an end to the humans but Noah found favor in God's sight (Gen. 6.8). God tells Noah to go into the ark and take with him seven pairs of clean animals, seven pairs of all birds, and one pair of each unclean animal. And we read Noah did so. The rains came for forty days and the waters covered even the mountains and all flesh on the earth died. According to J the flooding lasted 150 days. Then Noah went out, built an altar to the LORD, and offered sacrifices of each of the clean animals and birds. And again, we see the story is complete in itself.
So, were there two or fourteen of the animals? Both but it really depends on which story you read. I suggest perusing the selected passages (all of J and then all of E) to see the cohesiveness of each story. Not only will you experience the flavor of both authors, you'll have the opportunity to decide for yourself how many animals Noah took on board.