You don't indicate why you need to do this so the following may be rather more than you need. However, this finds all case insensitive matching keys and reports them:

use strict;
use warnings;

my %hash1 = (TEXT => 25, Text => 25, Wibble => 20);
my %hash2 = (text => 25, TexT => 25, wibble => 20);
my %h1Keys;
my %h2Keys;

push @{$h1Keys{lc $_}}, $_ for keys %hash1;
push @{$h2Keys{lc $_}}, $_ for keys %hash2;

my @common = grep {exists $h2Keys{$_}} keys %h1Keys;

print "Hash 1 keys \[@{$h1Keys{$_}}\] match \[@{$h2Keys{$_}}\] in hash
+ 2\n"
    for @common;
[download]

Prints:

Hash 1 keys [Wibble] match [wibble] in hash 2
Hash 1 keys [TEXT Text] match [text TexT] in hash 2
[download]

BTW, always use strictures (use strict; use warnings; - see The strictures, according to Seuss).