I was looking at these and I realized that there was spacing in between the 6 in the nine on the 1967 quarter and I was wondering if anybody else noticed these issues or have had any other quarters like them
You might try this. Take a piece of aluminum foil and press downwards to make a copy of the design. Then go to the next coin and make another copy and then the third. If you see then side by side you might get a better view on them. Then if one still looks different, notice if it is shorter in height? If so then the die was polished removing part of the base of the devices. Making the design look not as tall and farther apart.
That will explain why they are different. Let us know what you find out.