If you change your loop to something like this is should work:

my $iname;
while(<LST>)
{
   $iname=$1, next if /port-channel (\d+)/;
   next if !defined $iname;
   $hash->{$iname}->{$1} = $2 
        if (/switchport description To (\w+) ([\d\.]+)/);
   
   $Rec2->{$iname}->{$1} = $2 
        if (m|(fc\d+/\d+)\s+\[(\w+)\]|);
}
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Note, there is one small difference with the results you got from your code. Im sure you can see it, and fix it if its important:-)

gc