Attach (recommended) or Link to PDF file here:
[multiple.pdf](https://github.com/mozilla/pdf.js/files/6344777/multiple.pdf)

Steps to reproduce the problem:
1. Write something in a field

What is the expected behavior? (add screenshot)
The 3 fields must have the same value

What went wrong? (add screenshot)
The 2 other fields are empty

The three fields share the same name `Text3`.
It works as expected in Adobe and Chrome.
if (this.pinned) {
      this._hide(true);
    } else {
      this._show(true);
    }
  }
  /**
   * Show the popup.
   *
   * @private
   * @param {boolean} pin
   * @memberof PopupElement
   */
  _show(pin = false) {