Hi Philb
Is that a dig

I am surprised you did not answer the question first. When I looked up the catalog prices I was surprised at the price of the overprinted 1908 issue.
I have a little specialized section in my collection of the "Numeral Issues", varieties, printings, etc.. Therefore, I am pretty familiar with them. Unfortunately I do not have any blocks so that the spacing between the stamps can be measured.
There is a great book on the issues. "The Numeral Issues of Colombia" by Myers.
Jerry B