I would just bite the bullet and buy the extra pots/media. Nepenthes can be very sensitive to root damage, and growing two plants in one pot might cause you some considerable headache in the future. Just some helpful advice, especially since you look to be new to this.
Regarding media, a 50/50 peat perlite mixture can break down pretty quickly compared to some other more resilient mixes. I like to use a mixture of peat, perlite, orchid bark, and long fiber sphagnum moss. I first layer the bottom of the pot with orchid bark to increase drainage, and then use a 1:1:1 mixture of peat and perlite and LFS. I also repot most of plants annually in the spring, where dead material gets clipped back, a healthy spray of systemic insecticide (for insurance), and all new media. There is no right answer, and there is a multitude of media types you can use out there. It mostly depends on frequently you want to water your plants, I like having the peat in the mix because it holds water fairly well without getting waterlogged due to the rest of the mix. Everybody has their personal favorite, look around and do some reading and you should be good to go.