rear calipers wont fit new pads s14

[One_love_silvia]

hey guys. so i was trying to swap in some new but used (low mile) pads into my rears, and for some reason, i cant fit 2 new pads into one caliper, so i replaced the back pad with the new one, and kept the front pad there. still has abt 2mm of life left, but thats not much.

but for some reason, thats all that fits. the top bolt part of the caliper wont go on wen i try and put the caliper teeth over the pads. there is plent of room INSIDE the caliper, but the length from the teeth to the top bolt part is too small for 2 new pads...
strange thing is, the 2 new pads im trying to get on, came off my friends s14
same year, same model, same every thing.
i think my cars just retarded...

anyone know wtf is going on?
if u can make any sense of what i just said? lol