Thanks for the additional information; that really helps clarify what’s happening. Your description of the male’s behavior after being introduced to your tank makes it clear that he was also affected right from the start. Nope, falling off their hitching posts is definitely not normal behavior, but it is typical of the type of equilibrium problems seahorses have when they been exposed to high ammonia levels. So is leaning up against things or even lying prone on the bottom from time to time.
Based on these new details, Andrea, it does sound like your seahorses problems are probably due to exposure to high levels of ammonia in the shipping bags and during the acclimation process. I think they would both benefit from treatment with methylene blue as soon as possible.
In the meantime, increase the aeration and surface agitation in your seahorse tank (add and extra airstone if necessary) to improve the level of dissolved oxygen in the water, turn off the aquarium reflector and leave the tank dark for the next couple of days, and give the seahorses as much peace and quiet as possible while they recover. Just provide them with a stress-free environment and leave them alone to recuperate. Add some "feed-and-forget" live food that will survive indefinitely in a marine aquarium until it’s eaten, such as the red feeder shrimp from Hawaii (Halocaridina rubra, a.ka. Volcano shrimp) or live adult brine shrimp, but otherwise don’t pester them. They should be feeling much better soon.
Best wishes with all your fishes, Andrea!