Lawyers reuse letters, pleadings, and legal docs all the time. A quick copy and paste, coupled with a find and replace ... It's part of practicing. Sometimes, we even borrow language we like from other lawyers and cases.
But more often than any practitioner would like to admit, copy and paste errors, usually in the form of omissions, occur. You know exactly the error being described here. When you forget to paste over the last client's name that was used on a form, or forget to change a pronoun.
And on the subject of pronoun confusion, depending on how you set up your forms, your boilerplate could be expressing gender bias without you ever even realizing it.