with sub pop, pete just let's them use any piece of pre-existing artwork they want. then the lettering is added after the fact by somebody else.
this was probably done that way.
but, not all of his posters are done that way. but most of the subpop stuff tends to be.
In one of Pete's books, he's got a picture of a japanese gigposter that used the entire page that this panel is from, and all the speech bubbles were filled in with bands and venue info. That was cooler than this.