Students always have the option to resubmit their assignments. As an instructor, you can decide how to handle assignment resubmissions.
You do have the option to set availability dates for each assignment. Availability dates can restrict the dates that an assignment can be submitted.
All assignment submissions can be viewed in SpeedGrader. Students will not be able to view their previous submissions after resubmitting unless you reupload the assignments to Canvas.
Student View for Resubmit Assignment
Students will see a Re-submit Assignment link in the Sidebar below the Assignment submission details.
View Assignments in SpeedGrader
Open the student's Assignment in SpeedGrader. When a student has submitted multiple submissions, you can view them by clicking the drop-down button.
Viewing Older Submissions
If you view an older submission, Canvas will warn you that the submission you are viewing is not the most recent version.
Set Assignment Availability Dates
If you want to keep students from resubmitting assignments after a certain date, you can change the Assignment availability dates. Next to the date you want to change, choose the Calendar icon.
Set the date and time the assignment availability date by selecting a date  and time . Click the Done button .