#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my @array = ("V12345:name_test", "V12345_name_test");

my @final = ();
foreach my $str (@array) {
    if ($str =~ /[\w]+:/) {
	my @elements = split /:/, $str, 0;
	my $tmp = $elements[0] . "_" . $elements[1];
	push @final, $tmp;
    }
    next;
}

print Dumper \@final;

__END__

$ perl test_2.pl
$VAR1 = [
          'V12345_name_test'
        ];