I am not sure about the UD before the signature, but that is very intresting. However, I will say that it would be pointless to try to invalidate your signature on a traffic citation. The citation is not an admission of guilt. It is merely a promise to do one of the three options that you are presented with by the Deputy/Officer. Only one time have I seen someone refuse to sign the citation, and after several warnings they were handcuffed and taked "one adult male 10-15, 10-51 CJ (county jail)." Therefore, it is always good to sign first and fight later.
However we did have an illegal alien, Mexican to be exact, I wrote him out 5 tickets and he refused to sign them all. He threw them all up in the air and proceeded to tell me he wouldn't sign any of them. All he wanted was some more beer (after a DUI arrest), and some chicken and rice. I will admit that he was a funny character. Had we not of already been inside of the jail giving him a breath test, he would of went for not signing the tickets.