I'm thinking of being in two sexual relationships at the same time.
I am very shocked to hear this. Have you cheated with another person already?
No, but I think I might like to be.
While there are people who engage in open relationships and polyamory, it requires a lot of rules and open communication in order for such relationships to work. If you want to be in an open relationship, you should get the consent of everyone involved so that they do not get emotionally hurt when they find out you have multiple partners. Additionally, you need to practice safe sex when with multiple partners in order to prevent any possible spread of STDs.
I love the idea of secretly having two people that I can play with.
If the adults you are going to have sexual activities with are consenting adults, then you can proceed sleeping with them, but relationships aren't something you play with and they are serious, and people's feelings can get hurt if there's infidelity involved. So I hope you don't cheat on your partner and be loyal to them.