In my opinion, the best way to ruin a cover letter is to send it to the wrong person or company. When looking for a job, it's common to apply for multiple jobs in one day or one weekend. Since you're saying the same thing, a routine of copying and pasting or starting from a template means you have a higher risk of screwing things up.
Regardless of what your cover letter Writer UK says, I can guarantee you will not pass human verification if you mention the last company you applied to.
