If you collect mint sheets or plate blocks of stamps, especially from the late 1960s or 1970s, you’re probably going to find a number of items that have staple holes in the margins. Staple holes do exist on sheets and plate blocks from other years too.
I’ll be honest. I don’t know why the staple holes are there. However, I do know that the staples were used by the USPS. Perhaps they were used to secure panes of stamps together for shipment to individual post offices? Therefore, staple holes are “normal”.
Sometimes a customer will question the staple holes in the margins of the plate blocks they buy. There may be a few collectors that frown on the staple holes and consider them damaged copies. Most collectors and dealers consider this normal. That’s the way it came from the post office. That’s the way it’s collected. If you find staple holes in your mint sheets or plate blocks, don’t worry. They are perfectly normal. There is no price difference.