While I have knowledge of Outlook and fax and picture viewer,
I use neither and don't know exact details of all features.
However, until someone responds that has actual experience,
let's proceed.
1) You open a brand new email.
2) You click to attach a jpg file.
How many files do you see showing as an attachment in the
email?
It should be only 1 file. If it shows 2 or more files on the email,
you did something wrong. Only the files that show on the email
itself are the ones that are attached.
Another way to verify that, is to look at the size of the jpg.
Let's say the size is 100,000 bytes (100KB). The email will add
some weight to that figure, maybe the final email size will be
approx 130KB. If you actually have 2 jpgs attached, assuming
the same size, then the email will be 260KB. So, if your email
isn't that big, by reason, you must have only 1 jpg attached.
To be able to see filesize, save it to your draft folder and look
at the filesize column. Hopefully you have that column enabled.
Once you open that 1 jpg in picture viewer, maybe it retains a
list of files that you have attached previously, for your
convenience? So in case you ever want to know what you have
sent in the past?