Satoshi said "So they are similar after all." so it's not like he was completely surprised by the Joi's being the same.
I wouldn't be surprised if Ash did this to Officer Jenny, next time he meets one (after meeting Sanyou's Officer Jenny).
Did anyone catch the tune that was playing on the intercom system at the Pokemon Center? It is the chime that they use in the games to tell you all your Pokemon are healed. Clever, huh? It took me a while to get that reference because I haven't played the games in years and I had to look it up just to be sure.