both of those are png files. even though you added .jpg at the end of the title, its still a .png (it just got renamed to "2ewh3yc.jpg.png". you have to go through a different process to change a png file to a jpg, but thats a different story.
you can tell an HA is a png file if you put it somewhere with a colored background and you can see that the white area was transparent.
ex:
the first one would be a PNG because you can see its transparent. the second would be a JPG because the white background shows up.
i dont know how yours came up the way they did. they were half the size of a normal avatar, and some of them were grainy and had white backrgounds. perhaps you copied the wrong code? it should be the very last URL in the tinypic boxes
if thats what you copied, then you probably saved them wrong or something, because tinypic should not convert pngs to jpegs
but you can also upload your avatars directly from your computer onto SF, instead of tinypic first.