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)



if (Array.isArray(options)) {
      const xref = params.xref;
      for (let i = 0, ii = options.length; i < ii; i++) {
        const option = xref.fetchIfRef(options[i]);
        const isOptionArray = Array.isArray(option);
        this.data.options[i] = {
          exportValue: this._decodeFormValue(
            isOptionArray ? xref.fetchIfRef(option[0]) : option
          ),
          displayValue: this._decodeFormValue(
            isOptionArray ? xref.fetchIfRef(option[1]) : option
          ),
        };
      }
    }
    
    
    
    
    if (isString(this.data.fieldValue)) {
      this.data.fieldValue = [this.data.fieldValue];
    } else if (!this.data.fieldValue) {
      this.data.fieldValue = [];
    }
    
    this.data.combo = this.hasFieldFlag(AnnotationFieldFlag.COMBO);
    this.data.multiSelect = this.hasFieldFlag(AnnotationFieldFlag.MULTISELECT);
    this._hasText = true;
  }
  getFieldObject() {