use warnings;
use strict;

while (<DATA>) {
    chomp;
    for my $to_add (qw[_float _auxpc2]) {
        ( my $string = $_ ) =~ s/^(.+?)(\s+?.+?)$/$1$to_add$2/;
        print $string, $/;
    }
}

__DATA__
lvtnfet      cmos20lpm      lvtnfet_b      symbol d g s b PROPMAP m=m