use strict;
use warnings;
use Data::Dumper;

my %h;
while (<DATA>) {
    while (m/(\w+)\s?:\s?(\S*)/g){
        $h{$1} = $2;
    }
}
print Dumper \%h;
__DATA__
firstName : firstValue
          Name2: Value2
          Name3:Value3            Name4:value4
Name5:             Name6:
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Note that use of \w and \S is guesswork on my part - it works for the example you gave, but it depends on your data format if that's the right choice.

Please only use <code>...</code> tags for code, put your question into normal paragraphs. See Writeup Formatting Tips.