Insert PDF as File or Picture

When a PDF file is inserted into container field, using Insert File, the field will show a generic icon together with the name of the file.

When a large thumbnail of the PDF file is required for a 'quick look' on the layout, then the PDF is inserted using Insert Picture.

My normal approach, erring conservatively in the absence of information, has been to use 2 container fields, one for the Insert File, One Insert Picture for the thumbnail.

This does double the data size however; as might be expected. Not an unacceptable issue, but is it avoidable?

Curiously if the field content is exported from either the InsertFile or InsertPicture then the result is a copy of the original PDF, (with any password protection preserved). So it doesn't seem to matter whether the PDF is inserted as a File or Picture initially, if the output is the same. The only minor difference is that the exported creation and modification system level timestamps on the file will reflect the export; not an issue.

In other situations the PDF is stored external to the database, but this particular situation does not allow that. The solution requires that the PDF is stored in the database table.

Is there something more occult going on, or is it sound practice to insert a PDF as a picture when integrity of the original PDF data is the real requirement. It just feels that Insert Picture preserving the PDF format is somewhat anomalous.