A variety, yes. Scarce, no. The SRC (Sears, Roebuck & Co.) and MW (Montgomery Ward) overprints on precancels were two of the most prolific users of precancels, so they are very common. Since the stamped overprint "SRC" and date would be applied by the business, many varieties, overprints, etc., were created ... some intentional and some accidental. The challenge to a collector is to find the elusive cities and/or dates to complete a specialized collection.