(1) Subject to such regulations as the Commissioners may think proper to make, and to the production of such evidence by statutory declaration or otherwise as the Commissioners may require, allowance shall be made by the Commissioners for stamps in any of the following cases:
(a) the stamp on any material inadvertently and undesignedly spoiled, obliterated, or by any means rendered unfit for the purpose intended, before the material bears the signature of any person or any instrument written on the material is executed by any party;
(b) any adhesive stamp which has been inadvertently and undesignedly spoiled or rendered unfit for use and has not in the opinion of the Commissioners been affixed to any material;
(c) any adhesive stamp representing a fee capable of being collected by means of such stamp which has been affixed to material where a certificate from the proper officer is produced to the effect that the stamp should be allowed;
(d) the stamp on any bill of exchange signed by o
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