I've checked the link you provided to Percy's post and, as Catholic Scientists says, his point was that the order of creation given in Genesis 1 is different from the order given in Genesis 2.
The fact that both are supposedly sequential is in the surrouding text giving reasons for the creation of man and animals.
Genesis 1KJV
24And God said, Let the earth bring forth the living creature after his kind, cattle, and creeping thing, and beast of the earth after his kind: and it was so.
25And God made the beast of the earth after his kind, and cattle after their kind, and every thing that creepeth upon the earth after his kind: and God saw that it was good.
26And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.
27So God created man in his own image, in the image of God created he him; male and female created he them.
So right there God made man AFTER he made animals to rule over the already created animals.
Genesis 2 KJV
15And the LORD God took the man, and put him into the garden of Eden to dress it and to keep it.
16And the LORD God commanded the man, saying, Of every tree of the garden thou mayest freely eat:
17But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.
18And the LORD God said, It is not good that the man should be alone; I will make him an help meet for him.
19And out of the ground the LORD God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof.
20And Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field; but for Adam there was not found an help meet for him.
And here we can see that man was created first and the animals were created so he wasn't alone.
By giving this reason in Genesis 2, the text must be sequential. If the animals were created because man was alone and it wasn't good for him to be alone, that explicitly states that the order is man then animals. Yet in Genesis 1 the animals were already there when man was created, so he couldn't have been alone and needing animals.
That's the contradiction that Percy was highlighting in his post. The reasoning given in the two chapters shows that the creation order of man and animals in each chapter is sequential, otherwise the reasoning stated makes no sense at all.
So there's my evidence for this part of the two accounts being sequential - the language used in the accounts. What evidence do you have that they're not sequential?