Let’s look at the context.
1 And the LORD said unto Noah, Come thou and all thy house into the ark; for thee have I seen righteous before me in this generation. 2 Of every clean beast thou shalt take to thee by sevens, the male and his female: and of beasts that are not clean by two, the male and his female. 3 Of fowls also of the air by sevens, the male and the female; to keep seed alive upon the face of all the earth. 4 For yet seven days, and I will cause it to rain upon the earth forty days and forty nights; and every living substance that I have made will I destroy from off the face of the earth.
5 And Noah did according unto all that the LORD commanded him. 6 And Noah was six hundred years old when the flood of waters was upon the earth. 7 And Noah went in, and his sons, and his wife, and his sons’ wives with him, into the ark, because of the waters of the flood. 8 Of clean beasts, and of beasts that are not clean, and of fowls, and of every thing that creepeth upon the earth, 9 There went in two and two unto Noah into the ark, the male and the female, as God had commanded Noah. 10 And it came to pass after seven days, that the waters of the flood were upon the earth.
11 In the six hundredth year of Noah’s life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened. 12 And the rain was upon the earth forty days and forty nights.
13 In the selfsame day entered Noah, and Shem, and Ham, and Japheth, the sons of Noah, and Noah’s wife, and the three wives of his sons with them, into the ark; 14 They, and every beast after his kind, and all the cattle after their kind, and every creeping thing that creepeth upon the earth after his kind, and every fowl after his kind, every bird of every sort.
Is there an error, or inconsistency here? No.
What is here is a statement of God’s commanding Noah to enter the ark, and Noah’s obeying God. Then there is a statement concerning the time of Noah’s entering into the ark and the flood beginning.
These are not two separate entrances into the ark. These are speaking of the same entrance in two different manners.