ip_everywhere
I did receive your PM, and I did read your situation on this thread previously. However, you should know that I'm not obligated to answer to any post/situation even though someone calls my name for my input or send PM to me. I choose to answer only those posts, which seem important to me in my opinion. Besides, I'm a very busy person. Means-I've other more things also in my life to deal with it. Hope, you now understand my situation.
About your specific situation then you must need to know first that whenever you would sign anything then you will be legally responsible for all the facts written on the paper that you are signing even if you might want to call it "unknowingly", or "by mistake". And then it wouldn't be a matter whether you were able to read it thoroughly or not before signing it. Because if a document was not read before it’s signing then it was your stupidity, and not anyone else. Therefore, you would always need to prepare to pay the price for your mistake. You cannot expect everything to go away just because you want to. Every action has its reaction. Besides, nobody pointed a gun on you to have signed that Voter Registration. So then, how can you even say now that clerk at DMV was "making to sign" you? It is seemed nothing more than just a lame excuse.
To be honest, your case would completely be on the mercy of adjudication officer, depending on how officer would take this issue as to his/her own judgment on this. Why? Because, even though you had cancelled your Voter Registration Card (obviously later on), yet the fact still remains untouched that you DID claim to be a US citizen, one way or another, regardless of whatever tales you might now have to justify it. And, even though you did not vote, that doesn't mean that you did not claim to be a US citizen.
Further, if you are following up or reading my posts for a while on this forum then you obviously know that I don't care what other people (including attorneys) have to say about a particular situation. Because, I express opinions based upon my OWN knowledge about facts/laws/experiences, and not based upon other people's knowledge. With that note, I would say-
(1) Have you realized that you are a VERY lucky person as you have a letter from DMV wherein it states very clearly that a Voter Registration Card was issued to you BY ERROR, and it also states that you never voted? This letter is a deal breaker in your case. Why? Because, even if USCIS might find out somehow about you having registered for a Voter Registration Card as claimed to be a US citizen, they would still believe that it was because of the mistake of DMV. And, they would also believe that you have nothing to do with this at all. That means- you have a "lifesaver" (DMV letter) in your possession, which could definitely save you from deportation, which could have been a done-deal in your case otherwise. By making such statement on that letter, DMV is taking the whole fault on itself rather than blaming you for this even though you are 100 billion % guilty for this. How strange is that some people can easily get away even though they might have done a grave mistake in their life, but on the other hand-it is almost impossible for others to get away even though they were involved in a petty stuffs. It is very strange, isn't it? By the way, I'm wondering how did you know what is written in DMV letter if letter is sealed. Did they give you the copy of that letter too for your record?
(2) It is very likely that USCIS would never find out that you ever registered for Voter Registration, especially when I already told you previously that USCIS has no way to know whether or not someone claimed to be a US citizen except in a very limited obvious situations. This might also be the reason why some people were able to get away being in this situation. That means-you will also get away for doing "murdering". Just kidding. Means-all this mess won't create any problem to you as you have a "magic torch" in your hand, obviously DMV letter.
Just a final note. Never compare your case with someone else. Just because other people were able to get away in the past, that doesn't mean that you will get away too. Don't you know that each adjudication officer is different and unique in his/her thoughts/modus operandi? Do you think the same officers who did not take this issue as seriously with other people will interview you? Each case is unique and individual. You cannot generalize your own case based upon others. And, always remember-you will always be responsible for your action, even if you might say it otherwise.
Good Luck.