This sounds like an erronious error, ie the error message displayed is not the correct error message. There was definitely an error but the error was not that you tried the same password as your current.
I hate erronious errors with a vengance, because they not only break user workflow but they break helpdesk work flow as well then it gets escellated to an engineer who quite often cant fix the actual erronious error but knows what the actual issue is and fixes that anyway.. meaning the erronious error never gets fixed and will mow hang around to chew up everyones time all over again.
such a silly way to waste so much time, over and over.