Since people are pretty busy, it is common for LOR writers to ask people to draft their letter and they add or subtract from it. This is pretty useful because it saves them time and YOU can control what is included in there. LORs are very important-- I have high stats and I believe I was rejected my first round because of a very poorly written letter from a supervisor I was close with. I found out the letter was poorly written because she said she would use the letter she wrote for me as a template for another employee she wanted to write an LOR for. The employee showed it to me in a panic because the letter was poorly written and vague even though we both had close relationships with her. The next year, I drafted my own LOR for another letter writer got into a bargain competitive MOT program. My LOR writer told me that she just made a few changes to wording and grammar, but the content stayed mostly the same.
If you or anyone else needs a copy of the letter draft as a guide, private message me for more information.