To clone a pipe, either within a company or between two companies, you need to have admin permission of the pipe you want to clone as well as permission to create a pipe in the company.
Given that you have the necessary permission, the first step to clone a pipe is opening the pipe, clicking in the gear icon in the upper right corner of the screen, then on pipe settings.
Inside the pipe settings, find the 'clone to' option in the lower left corner. If you're not a member of more than one company, simply click on it to clone the pipe. If you are, click on it, select the company you want to clone the pipe to and wait a couple of seconds while the copy is created.