Complex sentence: In 1993, they toured supporting Nirvana on the In Utero tour, and in 1994, "Last Splash" received a platinum certification by the Recording Industry Association of America, and the band secured a prime spot on the Lollapalooza tour.
Split into simpler sentences: In 1993, they toured supporting Nirvana on their In Utero tour, and in 1994, "Last Splash" received a platinum certification by the Recording Industry Association of America. Also in 1994, the band secured a prime spot on the Lollapalooza tour.