Expected Output

  { 
'1'=> {
      'clz=>'nit'
      'degree'=>'ph.d',
      'name'=>'teja'
      },
'1'=> {
      'clz=>'iit'
      'degree'=>'M.tech',
      'name'=>'teja'
      },####This block not coming in output

'2'=>{
       'clz=>'mit'
      'degree'=>'ravi',
      'name'=>'B.Tech'
}
};
[download]

A hash cannot have multiple values for the same key. You will need to rethink your data structure.

Consider storing array references as values instead of hash references as values:

 { 
'1'=> [{
      'clz=>'nit'
      'degree'=>'ph.d',
      'name'=>'teja'
      },
      {
      'clz=>'iit'
      'degree'=>'M.tech',
      'name'=>'teja'
      }],####This block not coming in output
'2'=>[{
       'clz=>'mit'
      'degree'=>'ravi',
      'name'=>'B.Tech'
}]
};
[download]

This change will also need changes in your code on how you fill the data structure and how you output your data structure.

I am new to perl. Could you please guide me how to achieve that.Thanks in advance.