Just for the fun of it: 

$_=<>;
1 while (s/(\w)\s(\d+)(.*)(\s\1\s)(\d+)/$1." ".($2+$5).$3/e);
print

[download]

Example call: 

$ cat test
a 1 b 3 c 5 a 2
$ ./samekey test
a 3 b 3 c 5
$ cat anothertest
a 1 b 3 c 5 a 2 a 3 b 3 c 5
$ ./samekey anothertest
a 6 b 6 c 10

[download]
s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

In reply to Re: How to read a file and add value for same key by Skeeve
in thread How to read a file and add value for same key by tony_ucdavis

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