Combining certain columns from multiple files based on a particular column , and not eliminating duplicate names - awk

Question

I had to combine values of 2nd columns from multiple files, based on the 7th column of all files, so based on Ed Morton's answer in similar question (Combining certain columns of several tab-delimited files based on first column) , I wrote code like this :
awk 'FNR==1 { ++numFiles}
!seen[$7]++ { keys[++numKeys] = $7 }
{ a[$7,numFiles] = $2 }
END {
for (keyNr=1; keyNr<=numKeys; keyNr++) {
key = keys[keyNr]
printf "%s", key
for (fileNr=1;fileNr<=numFiles;fileNr++) {
printf "\t%s", ((key,fileNr) in a ? a[key,fileNr] : "NA")
}
print ""
} } ' file1.txt file2.txt file3.txt > combined.txt
INPUT FILE 1 :
+-------+-----------------+----------+-------------+----------+-------------+-------------+
| ID | adj.P.Val_file1 | P.Value | t | B | logFC | Gene.symbol |
+-------+-----------------+----------+-------------+----------+-------------+-------------+
| 36879 | 1.66E-09 | 7.02E-14 | -12.3836337 | 21.00111 | -2.60060826 | AA |
| 33623 | 1.66E-09 | 7.39E-14 | -12.3599517 | 20.95461 | -2.53106808 | AA |
| 23271 | 2.70E-09 | 2.30E-13 | -11.8478184 | 19.93024 | -2.15050984 | BB |
| 67 | 2.70E-09 | 2.40E-13 | -11.829044 | 19.892 | -3.06680932 | BB |
| 33207 | 1.21E-08 | 1.35E-12 | -11.0793461 | 18.32425 | -2.65246816 | CC |
| 24581 | 1.81E-08 | 2.41E-12 | -10.8325542 | 17.79052 | -1.87937753 | CC |
| 32009 | 3.25E-08 | 5.05E-12 | -10.5240537 | 17.11081 | -1.46505166 | CC |
+-------+-----------------+----------+-------------+----------+-------------+-------------+
INPUT FILE 2 :
+-------+-----------------+----------+------------+-----------+------------+--------------+
| ID | adj.P.Val_file2 | P.Value | t | B | logFC | Gene.symbol |
+-------+-----------------+----------+------------+-----------+------------+--------------+
| 40000 | 5.43E-13 | 1.21E-17 | 17.003819 | 29.155646 | 2.4805744 | FGH |
| 32388 | 1.15E-11 | 5.12E-16 | 14.920047 | 25.829874 | 2.2497567 | FGH |
| 33623 | 6.08E-11 | 4.43E-15 | -13.8115 | 23.870549 | -2.8161587 | ASD |
| 25002 | 6.08E-11 | 5.40E-15 | 13.713018 | 23.689571 | 2.2164681 | ASD |
| 33207 | 2.03E-10 | 2.29E-14 | -13.009752 | 22.36291 | -2.8787392 | ASD |
| 13018 | 2.03E-10 | 2.71E-14 | 12.929201 | 22.207038 | 3.0181585 | ASD |
| 5539 | 2.24E-10 | 3.48E-14 | 12.810902 | 21.976634 | 3.0849706 | ASD |
+-------+-----------------+----------+------------+-----------+------------+--------------+
DESIRED OUTPUT :
+-------------+-----------------+-----------------+
| Gene.symbol | adj.P.Val_file1 | adj.P.Val_file2 |
+-------------+-----------------+-----------------+
| AA | 1.66E-09 | NA |
| AA | 1.66E-09 | NA |
| BB | 2.70E-09 | NA |
| BB | 2.70E-09 | NA |
| CC | 1.21E-08 | NA |
| CC | 1.81E-08 | NA |
| CC | 3.25E-08 | NA |
| FGH | NA | 5.43E-13 |
| FGH | NA | 1.15E-11 |
| ASD | NA | 6.08E-11 |
| ASD | NA | 6.08E-11 |
| ASD | NA | 2.03E-10 |
| ASD | NA | 2.03E-10 |
| ASD | NA | 2.24E-10 |
+-------------+-----------------+-----------------+
The problem is that the 7th column has repetitive names, and the code takes the first occurrence of a particular name, I want the results for all the repetitive names. I tried deleting each line of the code and understand, but couldn't come up with solution

Answer 1

Finally figured out answer by myself !
I just have to eliminate the line : !seen[$7]++ from my code , as by including that it would only consider the first occurrence of any replicated name of 7th column (nth column in general)