If they are a 'standard' tubular cam lock, either Home Depot or Lowe's will have a pretty good selection which you can purchase keyed alike. They will not have the CH751 keyed lock that everyone in the campground will have several though. There are also tubular key and combination versions from places like McMaster-Carr (
https://www.mcmaster.com/# )
Pull one off and measure the tube length then match at the big box store (also take it with you JIC you are unsure of your measurements as many are now soldin metric lengths.