You have non-unique representations, or multiple equivalent representations. That’s exactly the terms that are used. There is no single word.
Usually you have one (sometimes several, for example for Unicode graphemes) canonical references to make comparisons easier. The idea is that if you convert all your data to a canonical representation, then checking for equality becomes trivial.
But look at something more complex. “Figures on a chessboard” could be represented as a list of type, colour, position. If there are 32 pieces then you have 32! different representations for the same pieces. You can have a canonical representation: Same list format, but the piece on a1 comes first, then b1, c1 etc. Only one representation. It white figures first, then black, each in the order king, queen etc. You have a different canonical representation. If two boards use the same canonical representation then comparing them is trivial.
Or you could pick one of gazillions of totally different representations.