See Post 128. Go to the PDF and play with the instructions I wrote.
It is a nothing more and nothing less than a digitally manipulated image and speaking about "different typewritters" is about as meaningful as speaking about this gal's Body Mass Index (BMI).
Following an "IF" you can say most anything you wish.
If it was originally done on a standard form then it was done with two different typewriters.
There should be OTHER forms from the medical centers that MATCH these typewriters. If there are not, then it's probably just something put together up at Langley.