I asked my website manager if there is a way to tell if photos are "old" and he said he couldn't tell.

If someone had the time, they could do a google search for images to determine if any of the images posted here on the forum were also posted on another website or forum and when. While winning hands might be the same, it would be too much of a coincidence if the credit meters showed the same amounts, along with the angles that the photos were taken.