Add a column to a file

file d1 contain:

1       A
2       B
3       C
4       D
5       E
6       F
7       G
8       H
9       I

I have this script: test.script

#!/bin/ksh

DAY=`date +%y%m%d`
H=`date +%H`
D=`date +%d`
cat d1 | while read line
do
a=$(echo $line | awk '{print $1}')
n=$(echo $line | awk '{print $2}')
awk '{print $0, $n}' d1 >> d2
done

./test.script 

cat d2

1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I
1       A 1     A
2       B 2     B
3       C 3     C
4       D 4     D
5       E 5     E
6       F 6     F
7       G 7     G
8       H 8     H
9       I 9     I

I expect:

1	A	A
2	B	A
3	C	A
4	D	A
5	E	A
6	F	A
7	G	A
8	H	A
9	I	A
1	A	B
2	B	B
3	C	B
4	D	B
5	E	B
6	F	B
7	G	B
8	H	B
9	I	B
1	A	C
2	B	C
3	C	C
4	D	C
5	E	C
6	F	C
7	G	C
8	H	C
9	I	C

on and on.....

Given that:

awk '{print $0, "A"}' d1

1	A	A
2	B	A
3	C	A
4	D	A
5	E	A
6	F	A
7	G	A
8	H	A
9	I	A

Thanks!