Draft email inline images duplicated exponentially when adding PDF attachments via Graph API

Describe the bug

When creating a draft email with a signature containing inline images (e.g., 6 images), the Graph API initially returns the correct number of attachments (6). However, after adding a PDF attachment to the same draft, the API returns duplicated inline image attachments (13 total - 6 original + 6 duplicates + 1 PDF). On subsequent API calls, the inline images continue to multiply exponentially (e.g., each inline image appears 4 times on the next call).

Expected behavior

Initial draft creation: 6 inline image attachments
After adding PDF: 7 total attachments (6 inline images + 1 PDF)
Subsequent API calls should maintain the same 7 attachments without duplication
Inline images should appear only once regardless of how many times attachments are added or the draft is accessed

How to reproduce

Create a draft email with a signature containing 6 inline images
Call Graph API to retrieve attachments - confirm 6 attachments returned
Add a PDF attachment to the same draft via Graph API
Call Graph API to retrieve attachments - observe 13 attachments (inline images duplicated)
Make another API call to retrieve attachments - observe inline images now duplicated more times each
Each subsequent call continues to duplicate the inline image attachments

SDK Version

Latest

Latest version known to work for scenario above?

No response

Known Workarounds

No response

Debug output

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### Configuration

_No response_

### Other information

_No response_

Start by reproducing the draft-email sequence described in the issue: create a signature with six inline images, add a PDF through the Graph API, and retrieve attachments after each call. Investigate the SDK behavior around attachment handling; done means the six inline images remain single instances and the PDF is the only additional attachment across subsequent calls.