We have a SQL script that can copy attribute values from one attribute to another. However, in this case, I'd recommend just updating the field type of existing attribute from 'Image' to 'File'. The one thing to be careful about when updating field types though is the attribute qualifiers. Each field type has unique qualifiers that need to be set. an "Image" field type has the following three qualifiers: binaryFileType, formatAsLink, and img_tag_template. the "File" field type has only one qualifier: binaryFileType.
Here's the SQL I ran to change the field type on your attributes:
update [Attribute]
set FieldTypeId = 32
WHERE [Id] IN (26695, 20261)
delete AttributeQualifier
where attributeid in ( 26695, 20261 )
and [key] in ( 'formatAsLink', 'img_tag_template' )