First point: It's y'all (you all), not ya'll (ya all).
Second: IFC does not have same rules as NPC. If you sign a bid, you are not bound to that bid for 1 year. You can depledge or not initiate and re-rush the next semester. However, the pledge does need to officially de-pledge from the fraternity. If he has not de-pledged or been blackballed (or kicked out in any way) from his fraternity, he is still bound by his bid. It isn't a common thing, but it's not uncommon, either. My chapter took 2 spring semester pledges. One had pledged KA and the other Pike the semester before, but both dropped out before initiations.
Sigma Chi also likes to tell how David Letterman initially pledged Sigma Phi Epsilon, but dropped out and pledged Sigma Chi the next semester.