Here are some duplicate samples I ran across during my holiday cleanup. All are standard 39 mm in diameter.

The notched chip doesn't have a Chipco ad on the back.

The blue Matsui is a coin-inlay from Japan.

The B.C. Wills Small-Key chip is unusual in that it is blank on both sides and could be hot-stamped for a customer.

The red Paul-son with edge spots has an old logo.

The 2 crown design chips are the same on both sides without a manufactures ad.

Price is $6 each... I pay postage.