I split your post into its own thread.
The reason there is a one picture limit in the signatures is that any more than that, and they usually get stacked top-to-bottom, which makes a really long post space, even for one sentence.
If you want to do two pictures, the best way would be to use an image editing program (doesn't have to be a fancy one) to merge the two pictures side-by-side. That way, they're one image.

by MartinisMommy
Edit: Also, if you are looking at Maddie Lyn's post in the thread this originated from, Maddie doesn't actually have three pictures in her sig, it just looks like it. Those were actually put into the post itself.