cannot get the duplication

Question

On my Samsung Note4, I use the code clear content in Clipboard firstly:

ClipboardManager clipboard = (ClipboardManager) 
  getApplicationContext().getSystemService(Context.CLIPBOARD_SERVICE);
ClipData data = clipboard.getPrimaryClip();
clipboard.setPrimaryClip(ClipData.newPlainText("", ""));

Secondly, I open the message, copy an SMS by long press.

Then, I cannot obtain the duplication by the code as follow:

ClipData data = clipboard.getPrimaryClip();

But i can get the duplication in SMS edit box by long press