When you get into the really ancient stuff, there's simply very little to go on many times. The Sumerian texts were translated a little at a time over a long period of time by language geniuses.
Okay, but that sounds like you can make things seem the same, if you really want to. Again, even if the same historical figure is mentioned in both cases, it just means that two ancient texts agree in one place. It doesn’t prove anything else.