Why? Hemlock is still winning. I don't see why anyone should change their votes frankly.
If it comes down to an "anything but" vote, fine, but copperhead and hemlock are both pretty rich. I personally strongly prefer hemlock, but I have a hard time understanding an "anything but" mentality when the choice is between two of the three darkest brown options on the table.
I encourage everyone to stick with their top choices. This really doesn't need to be a partisan struggle. It can just be people picking their favorite option. I've always loathed the idea that votes cast for a non-winning choice are wasted.
And hey, if anyone is hoping for a later release in a favored color, then holding firm will only help demonstrate market interest. Change your vote if you change your mind. Don't change it to block other people's hopes.
(But if you do change your mind, you should change it to hemlock

)