You can either copy clips from one and paste to the other, or nest one sequence inside of another. Or copy from both and paste into a new sequence. Or nest both into a new sequence.
Export out from one computer, then bring that export to the other computer and into the other project.
If you want to do any further editing of your video once you have combined the two projects, you will have to copy the complete project (media and all other files, including the Premiere project file) from one computer to the other. The use of an external hard drive is convenient here. You can use the project manager to collect and copy all the project files from the internal drives to the external drive. Copy the entire folder onto a media drive in the computer to which you are bringing the project.
You can then Import the required sequence from the transferred project to the first project.