Can I play Minecraft 1.11.2 multiplayer using the same computer? If so, how?
for this you may require 2 accounts for Minecraft java version. You set up a server on your computer and then open up 2 Minecraft windows and play.
An alternative solution would be using the Bedrock edition of Minecraft.
The easiest way to do this would involve spinning up a virtual machine such as Virtual-box running Ubuntu or some other free Linux distribution. Download and install Minecraft in both the VM and your desktop.
The next step requires you to start Minecraft in both the virtual machine and your desktop. Once Minecraft is started on both machines you'll need to start a LAN server from the desktop or VM whichever is most convenient.
You can connect to the LAN server from the VM by using
localhost as the IP address as well as the port printed in chat. Set up a separate keyboard and mouse for the VM using this Superuser answer, and profit.
Disclaimer: I have not followed these instructions and it will probably lag unless you have a decent CPU and graphics card as well as quite a bit of RAM.