People's signatures can and do change. Mine changed drastically when I got married.
Actually, for the first few months after I was married, my signature with my new last name did evolve... it changed from being legible to being my first name, last initial, and something that looks like an ECG of a patient with a serious arrhythmia.
If you sign your name in one place using your initials and in another place spelling out your full name, you're still the same person and you still signed both documents.
I'm glad you were able to vote in the end.