Hi Boldra, the following can obviously be golfed but left this way for clarity. 
use strict; 
my %hash;
my @array=qw(one 1 two 2 two 20);
for (my $i=0;$i<@array;$i+=2){
   push @{$hash{$array[$i]}}, $array[$i+1];
}
for my $key( keys %hash){
   print "$key => @{$hash{$key}}\n";
}

[download]
UPDATE: Apologies to ELISHEVA whose answer above is almost identical with the added benefit of golfing too, I took far to long to reply and so hadn't seen that response

In reply to Re: my array is almost a hash, but keys are not unique. by Utilitarian
in thread my array is almost a hash, but keys are not unique. by Boldra

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