once when I had an Opel GT, my ex backed it into a concrete pole ,so we had to have the rear redone, fixed , painted...they did the same butcher job and filled the open seams, said :"it looks a lot better"....what they meant was: " it was a lot easier to do"

so ,those filled seams most likely means there was body work there for some reason ,and they just filled it...then matched other side if only one side needed work....just my 0.02