Some synonyms for the word "doubler" include "duplicate," "replicate," "match," "copy," and "twin." These words all share the meaning of creating two or more of something identical or similar. While "doubler" is often used in the context of doubling a value or cost, these synonyms also apply to doubling other things such as copies of a file or the number of items in a collection. By using a variety of synonyms, writers can avoid repetitive language and add interest to their work.