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Professor Smith I think I may have resent you work from last night but i was afraid to delete it beause i was afraid it would do something to the file. Can you let me know if it does.

You have at least two alternatives:

Alternative 1. Just highlight the part of the file that doesn't duplicate what has already been sent, right-click to copy, and paste into the Submit Work Form.
Alternative 2. Copy the entire file into the submit work form, then deleted the part you don't want.

Whatever you do, do NOT save the SEND file after opening it. That will preserve the original SEND file in case you need it later.