DUPLICATE. The double of anything.
     2. It is usually applied to agreements, letters, receipts, and the 
like, when two originals are made of either of them. Each copy has the same 
effect. The term duplicate means a document, which is essentially the same 
as some other instrument. 7 Mann. & Gr. 93. In the English law, it also 
signifies the certificate of discharge given to an insolvent debtor, who 
takes the benefit of the act for the relief of insolvent debtors. 
     3. A duplicate writing has but one effect. Each duplicate is complete 
evidence of the intention of the parties. When a duplicate is destroyed, for 
example, in the case of a will, it is presumed. both are intended to be 
destroyed; but this presumption possesses greater or less force) owing to 
circumstances. When only one of the duplicates is in the possession of the 
testator, the destruction of that is a strong presumption of an intent to 
revoke both; but if he possessed both, and destroys but one, it is weaker; 
when he alters one, and afterwards destroys it , retaining the other entire, 
it has been held that the intention was to revoke both. 1 P. Wms. 346; 13 
Ves. 310 but that seems to be doubted. 3 Hagg. Eccl. R. 548.