Actually melded lego pieces (the unreleased ones) are the result of parts getting stamped out while the machines are swapping the colors. Lego Employees like to take them to their kids.
To my knowledge it actually is illegal to sell those on Ebay. So yeah you got yourself a really rare misprinted-but-not-quite piece.
edit: it could actually be a proto but the vast majority of those outside lego's vaults are from what I described.