Dutch stamps with postage due?
It is known that in Belgium, a number of post offices were sent a stamp with the letter T to convert ordinary postage stamps into postage due stamps. T stands for tax. This was because there was a shortage of postage due stamps for a short period; it was therefore an emergency measure.
This emergency measure was applied during the months of October, November, and December 1919, during which only stamps from the 1915 series were permitted to be used.
From 1958, the stamp with the letter T was brought out of storage again, and we see various stamps likewise being transformed into postage due stamps in a similar manner and used as such.
To my surprise, I once came across a number of Dutch stamps on which a letter T was also printed. A serif letter T that resembled the letter T used in Belgium. But also T letters with a straight broad bar and one with a straight short bar. One printed in both black ink and dark purple ink.
Has anyone been 'playing' around with this, keeping the Belgian examples in mind? Have you ever seen similar Dutch 'postage due stamps'? The strange thing is that the letter T is printed on the stamps affixed to the postal item! That is in contrast to the Belgian stamps. Hopefully, someone has a definitive answer regarding the Dutch T. 
I do have Dutch letters in my collection bearing a T-stamp (the type at the top in your example, but not *on* the stamp); in those cases, additional postage had to be paid. But surely that is not what you mean.
Could it be that these T stamps were mistakenly placed on the stamp instead of next to it in Belgium?
View, for example, the fourth letter on the following beautiful website:
http://netherlandspostalhistory.blogspot.ca/2013/05/reduced-letter-rates-to-belgium.html
No Hans, the Belgian catalogue clearly states: “A number of post offices that did not have penalty postage stamps available used 1915 issue stamps for collecting penalty postage, which were invalidated with a stamp.”
The Belgian stamps shown in the above article are also depicted as such in the OCB catalogue under 1919 (Oct-Nov-Dec).
Show,
The letter on the website I mentioned was from 1936. In this case, the T was placed next to the Dutch stamp, but a slight 'deviation to the right' would have placed the T on the Dutch stamp.
Doesn't seem impossible to me.