I would never intentionally use a tag on a fawn, even if it were a piebald. We had a doe that was a piebald on our place there in Ohio that we called off limits, but you cannot control what the neighbors do though and she disappeared that same year. With that said I have shot a few fawns in years past and every time it was a single deer coming through and did not size it up well enough to determine how big it was. It happens. My first deer though was a button buck and it was actually a pretty big deer considering it was only that years fawn.