By your description, you want a hash of arrays. You can decode your data lines with a single regex like so,

my %data;
while (<INPUT>) {
    if (/^-- (\w+):(.*)/) {
        push @{$data{$1}}, split " ", $2;
    }
}
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The messy-looking array argument of push makes the value an array reference and avoids throwing away previous values. That way your data is permitted to continue a key later.