Some amino acids are coded by more than one codon (known as degeneracy of codons), hence on deducing a nucleotide sequence from an amino acid sequence, multiple nucleotide sequence will be obtained.

For example, lie has three codons: $AUU$, $AUC$, $AUA$ hence a depeptide. Met-lle can have the following nucleotide sequence: $(i)$ $AUG$-$AUU$$ (ii)$ $AUG$-$AUC$ $(iii)$ $AUG$-$AUA$ – And if, we deduce amino acid sequence the above nucleotide sequences, all the three will code for Met-lle