[FqOD4xih7Uq6m9Z]

There might not be 2^256 distinguishable objects but maybe someone can come up with 2^16 distinguishable objects and just string 16 of them together. If there is one character off in a string of 40 hexadecimal characters it is hard to notice but that would be easier to detect in a set of 16 symbols.

[ReactiveJelly]

Memorizing order in a set of 16 similar objects is too difficult for me

[FqOD4xih7Uq6m9Z]

I don't think you would need to memorize the order, just compare them side by side to check that they are the same.

[nemo1618]

If you have the other avatar available for comparison, you don't need to do so visually -- the computer can compare the raw bytes directly.