Question about deletion in nucleotide to amino acid sequence translation

[paulovic96]

Hey:
I have a question about the translation of amino acid sequence from a nucleotide sequence (bunch_translate()).
I understand the gist of the function but I struggle understanding the cases in which a deletion is inserted.
e.g. we have a nucleotide sequence with either length

37 (ny %% 3 == 1): TGTGCGAGTAAATCGAACGAC GGGGAAAGGCTACTGG resulting in
--> TGTGCGAGTAAATCGAACGAC NNN AC GGGGAAAGGCTACTGG

or

38 (ny %% 3 == 2): TGTGCGAGTAAATCGAAC GA CGGGGAAAGGCTACTGGG resulting in
--> TGTGCGAGTAAATCGAAC NNN CGGGGAAAGGCTACTGGG

For the 37 seq a additional "AC" is inserted after the "NNN" instead of dropping a "G" while for the 38 seq "GA" is simply dropped. Why is there a difference between those two cases?

Thank ! :)