C:\test>type junk.dat
1208782,abc
406744,def
367455,abc
283191,mps
226159,abc
197688,rxwz
137875,rxwz
115901,abc
107297,def
99213,mps

perl -nlE"($n,$k)=split',';$h{$k}+=$n}{say$_,':',$h{$_}for keys%h" junk.dat
mps:382404
def:514041
abc:1918297
rxwz:335563

##</code><code>##

perl -nlE"($n,$k)=split',';$h{$k}+=$n}{say$_,':',$h{$_}for sort keys%h" junk.dat
abc:1918297
def:514041
mps:382404
rxwz:335563