Stacked Spawners : whenever you mine a spawner with a telepathy pick u won't get the exact amount of the stacked spawner that was placed. instead you will get 1. To avoid this you must use a Silktouch pick without a telepathy pick (or just a silktouch pick in /kit tools or /kit godtools)
Yeah i notice alot of people doesn't really use the stacked spawners. maybe its because whenever for example u got a 100+ igs sometimes it acts like its only 1. but sometimes it dies rapidly. or they just dont know how to mine it all without loosing spawners