duplicate, extra - something additional of the same kind
Example:- he always carried extras in case of an emergency
duplicate, duplication - a copy that corresponds to an original exactly
Example:- he made a duplicate for the files
double, duplicate, reduplicate, repeat, replicate - make or do or perform again
Example:- He could never replicate his brilliant performance of the magic trick
duplicate - make a duplicate or duplicates of
Example:- Could you please duplicate this letter for me?
double, duplicate - increase twofold
Example:- The population doubled within 50 years
duplicate, parallel, twin - duplicate or match
Example:- The polished surface twinned his face and chest in reverse