They scan documents. The agent has to take the staples off...very annoying for them. Years ago I had sponsored my spouse, and spoke to my Case Officer directly (not a CIC agent that one talks to on the general number) who very kindly requested me not to staple the additional supporting document requested. She mentioned that they have to scan the documents, take the staples off and often the documents get stuck...blah blah...you get the gistHow do you know? Is there a request from IRCC that says 'don't staple'.
Use a paper clip instead OR feel free not to take this advice. Its your application at the end of the day...