my @array = (
"hello 1234 5698 7458",
"hi 1457 7459 6214",
"good_day 1458",
"hi 1258 3658",
"good_morning 4758",
"hi 1453",
);

my %indexedArray;
my $key;

foreach (@array) {
	$key = (split())[0];
	if ( defined $indexedArray{$key} ) {
		$indexedArray{$key} = '';
	}
	else {
		$indexedArray{$key} =  $_;
	}
}

@array = grep(/.+/,values(%indexedArray));