Were these T4 information slips from the same company and revised or different jobs? The Canada Revenue Agency (CRA) advises not to file twice. They suggest waiting for your assessment to be done and to verify your Notice of Assessment when you receive it. Many times the CRA will have already made the adjustment for the added slip which was missing as they have in on record in your file.
For future use please see our article: How to Change Your Tax Return After You’ve Filed
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