Mostar issue is known for multiple printing errors, especially broken stars, pins around the stars, missing letters, large shifts, etc. So far, I have seen hundreds of these stamps but I have never seen an error as shown below...
1945 Mostar local provisional issue, No. 20, 20/20 Kn, coincidental error, line below the star and rectangle on the right of the Federativna. Probably unique error, most likely due to a foreign object on the printing plate. Ex Tiberio.
