Firstly thanks for coming to PSG, in answer to your question NO.
Photoshop does a lot of great things but acting out a scene from CSI is not one of them, maybe one day it might be able to, have you tried holding the letter up to a bright light on the off chance you can make out some of the under letter?
I would think you could use the eyedropper to find the cover color than reduce the saturation to see if any different hues are residing underneath. Also use the channels in curves to reduce the top color to a point where the hue between the two layers of ink maybe slightly different. Enough to maybe see the underlying ink. would be worth trying. unless it as signed with the same pen in exactly the same place, also ink pigments are different.
One thing you might try is an experiment. On a plain sheet of white paper, write something in one color and then scribble it out with another color, scan the image and see if your theory works. I'd be interested in seeing your results.