Multiple runners on multiple computers with the same tag

Hello, i've searched through all gitlab documentation and haven't found answer to this question, so i dont know if it's a feature proposal or an issue, but any answer would be appreciated. My problem is, i have two computers with osx on board, and i'm trying to register one gitlab-runner on each of the mac but with the same tag on it. So after successful configuration i've trigger pipeline for this specific tag two times concurrently, and both of them started only on one(first) gitlab runner on mac1. So obviously i turned off first mac to see if second one would get the same pipeline running again, and it does. So my questions is:

1. Whats the order for runners with same tag that will get pipelines, how is it choosing the runner that will get jobs as a first one?
2. Is there any way to make pipelines switch between multiple runners with the same tag?

My case: When pipeline is running on one computer there is a situation when another pipeline gets run concurrently, that's ok but if it happens multiple times the first one can last up to one hour because all the others runs and performance getting lower, and computer resources are distributed through all of the pipelines. I thought it would be neat to get second computer, register runner on it with the same tag and make some kind of switcher that will choose which runner on which computer to point out based on numbers of pipelines it's running at current time. So, if first one runs 1 pipeline and second one none, the next pipeline should be run on the second computer.