If you entered on a visa, trust me, they know -- the immigration people at checkpoints can look up to see where and when you've entered the country previously and whether or not you've overstayed your visa before. Whether that particular individual 'processing' you cares is another story, but they're supposed to care and in such a situation you are not supposed to be allowed back into the country.

My point is, don't rely on entering the country through a checkpoint if you leave after overstaying.