This is the 1895 2c postage due with the Postage Due overprint reading downwards. It is only available with a CTO bar cancellation. The most expensive variation would have the overprint reading upwards omitted in pair with a normal.
This 12c crocodile adhesive has the double overprint but unfortunately has some tone spots. Almost all the stamps in this issue have the double overprint variety. They are only available as CTO which is not surprising. You can draw your own conclusions.