Unmatching without a response is the best option when the both of you have accidentally matched with each other.
You don’t want to get into a situation where you respond out of courtesy to the accidental match who messaged you, only to have them respond back in anger because you let them know that it was an accidental match.
Yes, people can take it personally. No need to put yourself in this position.
Quietly unmatch. You don’t owe the person anything.