Word file used: 
[Formular_T.docx](https://github.com/mozilla/pdf.js/files/6907859/Formular_T.docx)

PDFs generated:
PDF 1: [Formular_T_default.pdf](https://github.com/mozilla/pdf.js/files/6907771/Formular_T_default.pdf)
PDF 2: [Formular_T_changed.pdf](https://github.com/mozilla/pdf.js/files/6907772/Formular_T_changed.pdf)

- PDF.js version: v2.9.359

Steps to reproduce the problem:
1. Create Word Document with Checkbox and check it.
2. Convert Word document to PDF using **Aspose.pdf** (for .net)

3. Extra: Change value of second Checkbox  in PDF 1 and save the file (PDF 2). The new File will show both Checkboxes checked in other browser, but only the newly checked one in PDF.js

Expected:
Checkbox is checked (pdf viewer from adobe/Chrome Version 92.0.4515.107 64-bit)
![image](https://user-images.githubusercontent.com/76941221/127659557-42be1cca-3c90-49b8-b224-70ee85aa1b30.png)

Result:
Checkbox is not checked (Mozilla Firefox/PDF.js)
![image](https://user-images.githubusercontent.com/76941221/127660064-e3cdc3f9-6887-4ae7-af27-d46cded69029.png)



this.checkedAppearance = normalAppearance.get(this.data.exportValue);
    this.uncheckedAppearance = normalAppearance.get("Off") || null;
    this._streams.push(this.checkedAppearance);
    if (this.uncheckedAppearance) {
      this._streams.push(this.uncheckedAppearance);
    }
    this._fallbackFontDict = this.fallbackFontDict;
  }
  _processRadioButton(params) {
    this.data.fieldValue = this.data.buttonValue = null;
    
    
    const fieldParent = params.dict.get("Parent");
    if (isDict(fieldParent)) {
      this.parent = params.dict.getRaw("Parent");
      const fieldParentValue = fieldParent.get("V");
      if (isName(fieldParentValue)) {
        this.data.fieldValue = this._decodeFormValue(fieldParentValue);
      }
    }
    
    const appearanceStates = params.dict.get("AP");
    if (!isDict(appearanceStates)) {
      return;
    }
    const normalAppearance = appearanceStates.get("N");
    if (!isDict(normalAppearance)) {
      return;
    }
    for (const key of normalAppearance.getKeys()) {