Japanese occupation Burmese one rupee, block distance?

My mother gave me some of her old notes she had received from her uncle who served in World War II. Among these is several Burmese rupee notes from Japanese occupation. The 1 Rupee however is confusing me a bit. I have two, the block letters are both BD, and on both notes, the gap between the edge of the D on the left and the beginning of the B on the right is exactly 67 mm, instead of 63 mm or 69 mm as I expected. I would identify it as P#14a2 based on the off-white paper alone, but the notes are worn and I'm not sure the color is not from age. Am I measuring wrong? Here is a scan of the note below. Thanks.

You have greases and a relatively rough note which could have reduced the distance as well as the precotion of your measurement could be of a mm or though.

At the end it is significantly larger then 63mm so I would go with the 69mm variant.

Can't say much about the substrate color, I find it hard on old notes that could have yellowed over the decades.