Now I am curious

In volume 1 of the Israel Plate Block Journal, there was mention of 2 different commemorative stamps that have multiple printing dates in the plate block. I went through the nearly 30 years of archives that I got from the SIP, and there was no other mention of what these two issues were, or what the two different printing dates were. Does anyone know what these issues were? I checked my Bale catalogs, and see no reference to this either. Any help would be appreciated.