The Tianyi Gourd only had one skill, and that skill was also called Transmute Monster.
But the Transmute Monster skill that it possessed and the Transmute Monster skill he gained from the Monster Transmutation System had two different effects.
The Transmute Monster Skill from the Monster Transmutation System was able to transmute monsters and produce Bloodlines, Evolution Pills, and Experience Pills. He could even get pieces of equipment out of bosses. Its second ability was to allow him to fuse with monsters and to increase his own power.
Meanwhile, Tianyi Gourd's Transmute Monster's first ability was to create monsters. That meant that he could create monsters with the gourd. Its ability was completely different than the one from the system. One was used to destroy life, while the other was used to create life.