My Son-in-law Is In Panama City (he's A Pilot)...and Was

My son-in-law is in Panama City (he's a pilot)...and was walking down the street...stepped on a manhole cover which flipped up and cut his leg just below the knee...wound looks to be 1/8 to 1/4 inch deep--about an inch and a half long. I advised him to get a tetanus shot, since he doesn't have documentation on the last time he rec'd one. He did go to a clinic there and there seems to be some confusion about IF he actually rec'd the shot. It didn't hurt going in at all and his arm is not sore (he got the shot this morning). So the question is...would it hurt if he got another shot just in case? Would a double dose (if he DID get the shot, which he's not sure of) hurt him?