I have three halves of Rushton double-bladed paddles - all three are somewhat the worse for wear, but not because of the copper tips. These came out of a livery in Canton, NY, so were presumably abused.
The paddle on the left has a copper tip that was put on in two halves, joined along the edge of the tip of the blade. The paddle on the right has a square tip, and the copper was first folded over the tip, then again over the sides (like a Christmas package). The paddle in the middle has the classic one-piece mustache tip. The shape of the mustache allows you to bend the copper to shape in one piece.
There is a description on this in Graham Warren's first book, "Making Canoe Paddles in Wood." It is too bad this book has become hard to find, because in my opinion, it is far better than his second book with Gidmark.