I am assuming that you had the recipe opened and changed the name at the top of the design page. The 'save' button then saves that recipe under that name and leaves the recipe open. If you check back to the folder where the recipe was stored, it should be listed under the new name. The old recipe name will be gone.
I use the save button when I am brewing to save data just in case some dumba$$ (like me) accidentally closes beersmith or the open recipe. If I want to change the name of the recipe, but keep the original recipe intact, I use the 'save as' button. This will also leave the recipe open in BeerSmith. If you want to save and exit the recipe, click the 'OK' button. Lastly, if you want to exit without saving the recipe, click the 'cancel' button.