#!/usr/bin/perl

use strict;
use warnings;

my $dir='whatever';
chdir $dir;

for (glob "*.*.*") {
    my ($u, undef, $v) = split /\./, $_, 3;
    my $dest="$u.$v";
    rename $_, $dest or 
      die "Can't rename `$_' to `$dest': $!\n";
    print "`$_' => `$dest'\n";
}

__END__